30th Annual Meeting
of the
American Association of Stratigraphic Palynologists
Program and Abstracts
edited by
Reed Wicander
Sarah Damassa
Paul K. Strother
September 14 - 19, 1997
Swope Center, Marine Biological Laboratories
Woods Hole, Massachusetts
Abstracts
Edited by
Reed Wicander
Central Michigan University
EVOLUTION OF THE MARINE ECOSYSTEM
Richard K. Bambach
Department of Geological Sciences, Virginia Tech, Blacksburg, Virginia 24061-0420, U.S.A.
For the first 2.5 billion years of the history of life, the ecosystem
was confined to the primary system of producers and decomposers. The potential
for the more complex ecosystems of the Phanerozoic only began to develop
about one billion years ago with the start of the radiation of the various
eukaryote crown groups. The first preserved record of an ecosystem that
includes a secondary component (consumers) appears in the Vendian.
A new physiological categorization of various animal taxa reveals underlying
patterns of diversity change that must relate to basic changes in ecosystem
structure in the marine realm during the Phanerozoic. There are four major
intervals with fundamentally different interrelationships of ecological
importance: (1) the Early Paleozoic (with its dramatic changes in diversity
and in dominance), (2) the bulk of the Paleozoic (during which diversity
fluctuated but did not trend up or down and diversity proportions within
the fauna remained stable and unchanging despite faunal turnover), (3) the
Mesozoic (where a new balance of diversity relations was maintained as diversity
increased), and (4) the Cenozoic (in which diversity has increased at markedly
different rates in different groups but a near constant proportionality
- the reverse of that maintained in the Paleozoic - has persisted).
Knowledge of how changes in the consumer side of the ecosystem that differentiate
these major intervals are linked to primary producers will be necessary
to integrate a full understanding of the evolution of the marine ecosystem.
Ultimately we must answer two questions: (1) what changes in the primary
ecosystem influence the consumer system and (2) what are the feedbacks from
consumers that influence primary producers?
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EVOLUTIONARY HISTORY OF MARINE DIATOMS: RESPONSE TO ENVIRONMENTAL CHANGE
John A. Barron
U.S. Geological Survey, MS 910, Menlo Park, California 94025, U.S.A.
Although the earliest definitive record of diatoms is from upper Lower
Jurassic rocks of Germany (~190 Ma), well documented records of diatoms
first occur in Lower Cretaceous rocks (120 Ma). The record of diatoms may
be longer, but the susceptibility of opaline silica diatom frustules to
destruction either by alkaline pore waters or by exposure to temperatures
in excess of 50°C limits the preservation of diatoms in older rocks.
Continued study of calcareous and phosphatic concretions, which protect
diatom frustules from dissolution, should add significantly to our knowledge
of the early history of diatoms.
The earliest preserved diatoms are dominated by resting spores, which are
common today in marine, neritic environments. During the Late Cretaceous
there was an explosive radiation of diatoms into the open ocean and coastal
upwelling regions. Diatomite first became widespread at this time. Diatoms
did not suffer a major extinction at the end of the Cretaceous; indeed,
>85% of the Cretaceous diatom species continued into the Paleocene. Presumably,
resting spore formation allowed diatoms to survive the environmental crisis
at the end of the Cretaceous. Although no mass extinctions of marine diatoms
have been observed during the Cenozoic, periods of relatively rapid evolutionary
turnover in marine diatom assemblages occurred near the early Eocene-middle
Eocene and Oligocene-Miocene boundaries, and during the earliest Oligocene,
early middle Miocene, latest Miocene, and late Pliocene. All of these intervals
were characterized by major rapid cooling at high latitudes and/or major
reorganization of ocean surface-water circulation. Distinctly provincial
diatom assemblages developed during the latest Cenozoic in the North Pacific,
the North Atlantic, the low-latitude oceans, and the Southern Oceans that
surround Antarctica.
The Paleocene and Eocene diatom assemblages were dominated by relatively
robust genera, while a trend toward more delicate forms began in the Oligocene
and continued to the present. This trend coincided with an increasingly
more vigorous circulation of the ocean's surface and deep waters. Enhanced
upwelling of deeper waters meant increased levels of silica and other nutrients
in the surface waters, especially seasonally in coastal upwelling regions.
Rapid growth of diatoms during seasonal blooms was probably aided by the
requirement of lesser and lesser amounts of silica in the construction of
their frustules.
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PALYNOLOGY OF THE SILURIAN ARISAIG GROUP, NOVA SCOTIA
John Beck
Boston College Weston Observatory, 381 Concord Road, Weston, Massachusetts 02193, U.S.A. and Boston University, Department of Geosciences, Boston MA 02215, U.S.A.
The Arisaig Group in Nova Scotia (western Avalonian Terrane) represents
one of the most complete sections of nearshore, siliciclastic, marine deposits
of Silurian age in North America. Facies changes throughout the unit are
gradual, rarely are the sediments coarser than silt, and virtually all the
samples examined were richly palyniferous. Combining information from invertebrate
paleontology, sedimentology, and palynology, the Arisaig Group can be subdivided
into three nearly complete depositional sequences, each bounded by a nearshore
or nonmarine erosion surface.
Given this context (i.e. gradual facies changes and continental shelf setting),
the deposits at Arisaig provide an ideal medium in which to study several
aspects of both marine and nonmarine organic evolution during the Silurian.
Acritarchs are the most abundant marine palynomorphs found in most samples
and provide a background "biomarker" to which the relative percentage
and type of other palynomorphs may be compared in depositional studies.
Of the 130 acritarch taxa identified throughout the section, the greatest
diversity occurs in middle to outer shelf deposits of the Llandovery, after
which overall diversity declines in keeping with global evolutionary patterns
and greater local depositional instability. Certain constraints on acritarch
distribution, such as the inability to characterize facies below the member
scale, were found to both limit and enhance the usefulness of acritarchs
in depositional and biostratigraphic studies respectively.
Similarly, nonmarine macerals (particularly spores and cryptospores) are
well preserved and diverse at Arisaig. Although they are not as abundant
as acritarchs, thirty-six species were found with the first major diversity
escalation event occurring in the Homerian. This event occurs well before
the first comparable evolutionary event provided by plant macrofossils which
do not become morphologically diverse until the latest Silurian/earliest
Devonian. This pattern is consistent with findings observed globally and
highlights the utility of nonmarine microfossils in understanding regional
and local evolutionary events. In terms of paleoecology, the increase in
recalitrant plant detritus into nearshore sediments during the mid-Silurian
probably affected the type and trophic structure of burrowing infauna. At
Arisaig, deep bioturbation and average bedding thickness of sedimentary
layers was observed to increase after this time. What other effects this
newly evolving resource had on the environment, such as sediment stabilization,
increased weathering, or enhanced nutrient release, await further study.
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PALYNOLOGY AND DEPOSITIONAL HISTORY OF LATE PLEISTOCENE AND HOLOCENE COASTAL
SEDIMENTS FROM ST. CATHERINES ISLAND, GEORGIA, U.S.A.
Robert K. Booth
Department of Biology, Georgia Southern University, Statesboro, Georgia 30460-8042, U.S.A.
The Quaternary history of the southeastern coastal plain is not well
understood, and the use of palynology has shown great promise in furthering
our understanding of past geologic, climatic, and vegetational changes in
the region. St. Catherines Island is a barrier island on the Georgia coast,
lying within Liberty County about 25 miles south of Savannah (31 37'N latitude,
81 09'W longitude). The sediments of St. Catherines Island are of Late Pleistocene
and Holocene age; understanding their relationship to other inland and marine
sediments is critical to assessing geological and biological changes that
have occurred in the region. Sediment cores from the island were analyzed
to determine ages, environments of deposition, and relationships to other
coastal and inland localities.
Three sediment cores were obtained using a vibracore; they comprise a transect
in the mid-southern portion of the island. The localities are known as Cracker
Tom Bridge, Cracker Tom Hammock, and Beach Pond. The sediment consists of
peat, shells, sand, and clay. Peat from 5.02-5.12 m at Cracker Tom Bridge
was radiocarbon dated at 47,620 B.P. Above this peat, lies an irregular
erosional surface which is, in turn, overlain by marine mollusc shells and
charcoal. The charcoal was dated at 6,020 B.P., indicating a depositional
hiatus of 41,600 years following the deposition of the peat. The subsequent
marine transgression resulted in the accumulation of the sediments which
make up the remainder of the strata in the three cores.
Pleistocene sediments deposited during low sea level were derived from inland
plant communities; the 47,620 year old Cracker Tom Bridge peat consists
dominantly of Woodwardia spores and other hydrophytic taxa. Regional vegetation
represented in the Pleistocene portion of the cores is dominated by Pinus,
Quercus, Carya, and Poaceae. Pollen of boreal taxa is infrequent, though
an indication of the presence of northern temperate forest in the region
is suggested by very low percentages of Picea, Tilia, Fagus, and Tsuga.
The Holocene portions of the Cracker Tom Bridge and Cracker Tom Hammock
cores are derived from near shore marine and salt marsh/tidal flat environments.
Composites, chenopods, and grasses are present as well as Pinus and Quercus.
Consistently present in small percentages are Carya, Myrica, Taxodium, Liquidambar,
and Nyssa. The Beach Pond core, taken from a pond lying ~50 meters from
the high tide mark, is palynologically characterized by an assortment of
fresh water elements (i.e., Azolla, Myrica, and Typha), and typical marine
palynomorphs (i.e., microforaminifera and chenopods).
Results of the palynological analysis of sediment cores from the island
attest to the stability of southeastern floral elements and plant communities
throughout the late Pleistocene in coastal Georgia. Even as sea level fell,
making the island a part of the mainland, and north temperate and boreal
species migrated southward, the familiar southeastern plant species remained
on the coastal plain.
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ANALYSIS OF PALAEONTOLOGICAL DATA ON THE INTERNET
Michael C. Boulter
University of East London, Romford Road, London E15 4LZ, United Kingdom
It is a fortunate coincidence that at the same time as we appreciate
the need for an inventory of all known fossil species, global computer networks
are becoming more sophisticated. Some examples of palaeontological databases
will be presented here and techniques to search and link these on the Internet
will be demonstrated.
The latest interactive programs allow such selected data to be downloaded
for mapping and analysis and examples of two major advances in data analysis
will be given. Thorne's biogeographic database of angiosperm families can
be plotted globally and palaeogeographic maps are also available when stratigraphic
data are given. The geological times of first and last appearances of all
biological families from the fossil record show an exponential curve, meaning
that biological evolution is a self-controlling system.
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A HOLE-Y ALLIANCE: CALCIODINELLOIDEAN ARCHEOPYLES IN DINOSPORIN CYSTS
Sarah Pierce Damassa
Consultant, 3 Ridge Street, Winchester, MA 01890, U.S.A.
Four undescribed species of organic-walled dinoflagellates having the
peridinialean archeopyle type 3A3I have been recovered from Eocene Miocene
sediments of the North Atlantic region. Species' ages and localities are
as follows: Priabonian, Deep Sea Drilling Project Hole 612, offshore New
Jersey, USA; Rupelian, Baldwin County, Alabama, USA; Chattian, Deep Sea
Drilling Project Hole 369a, offshore northwest Africa; ?Burdigalian, Deep
Sea Drilling Project Hole 338, Voering Plateau, Norwegian Sea.
The Priabonian and Rupelian species are so far represented by only one or
two specimens, and are not yet known in detail; however, the Chattian and
?Burdigalian species are both known from at least one hundred well-preserved
specimens. Although superficially very different in appearance, both the
Chattian and ?Burdigalian species consist of an autophragm ornamented with
features of low relief, and a prominent first apical plate which remains
attahced to the cyst and provides an easily recognized landmark for orientation.
The first apical plate and the bilateral symmetry of the remainder of the
archeopyle margin are the only evidence of tabulation in either species.
Isolated opercula are extremely rare.
The 3A3I archeopyle (three of four apical and all three anterior intercalary
plates involved; operculum simple, free) is typical of the subfamily Calciodinelloideae
Fensome et al. 1993, and has only been reported in organic-walled cysts
(e.g., Brideaux, 1977, from the Barremian of northern Canada). Lentin (1985)
suggested that such dinosporin fossils might represent linings belonging
to calcareous cysts. Implications for classification of the subfamilies
Calciodinelloideae and Ovoidimiodeae again focus attention on the relative
importance of tabulation vs. cyst wall composition in cyst/theca taxonomy
(Fensome et al., 1993), and suggest that integration of calcareous and dinosporin
processing techniques and research efforts might increase our understanding
of species with these characteristics.
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ENVIRONMENTAL CONTROLS ON THE EVOLUTION OF CYST-FORMING DINOFLAGELLATES
Barrie Dale1 and Amy Dale2
1Department of Geology, University of Oslo, PB 1047 Blindern, 0316 Oslo
3, Norway
2GeoResearch Consulting, Bakli, 2100 Skarnes, Norway
The evolution of organisms on Earth is generally perceived as a response
to changing environments through time. Here, we consider the possible role
of changing environments through the past 40 million years on the evolution
of present day cyst-forming dinoflagellates. Our ongoing global study of
cyst distributions in recent sediments provides a data base of 508 samples
and 227 cyst forms. Application of correspondence analysis has allowed us
to identify the two most important environmental trends accounting for most
of the variation in recent cyst distributions, respectively: latitude (=
sea surface temperature factor) and depth (= coastal to oceanic water mass
factor). Statistical analyses have allowed us to rank the cyst types according
to their numerical importance and environmental preferences.
For this paper, the 20 most common cyst types were assigned to four broad
environmental categories: 1) warmer coastal water (inhabiting equatorial
to temperate zones); 2) colder coastal water (sub-polar to polar); 3) cosmopolitan
coastal (both warmer and colder waters); and 4) oceanic. The known geological
ranges of these different cyst categories show significant trends: the three
warmer water types all have older geological ranges (Eocene-Oligocene to
Recent) as do six of eight cosmopolitans (Eocene-middle Miocene to Recent)
and the two oceanic cysts (late Oligocene to Recent), while the five colder
water species all have younger ranges (late Miocene-Pleistocene to Recent).
This strongly suggests that 1) the warmer water species have been able to
inhabit similar environments since the Eocene, though these are much less
geographically widespread today; 2) the colder water species are "new"
species which have evolved in response to the "new" colder water
environments created by glaciations since late Miocene time; 3) the cosmopolitan
species have survived since at least the late Eocene, due mainly to their
greater environmental tolerance; and 4) the oceanic species, similarly to
the warmer water species, have inhabited the stable oceanic water masses
since the late Oligocene.
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INTERNET RESOURCES AVAILABLE TO PALYNOLOGISTS
Owen K. Davis
Department of Geosciences, University of Arizona, Tucson, Arizona 85721, U.S.A.
The Internet has transformed computing, and has become a primary resource
and form of communication for some fields. Many palynological web sites
have sprung up in the last few years, offering a variety of useful information
including addresses for fellow palynologists, software, and data of various
kinds.
Three information transfer protocols are GOPHER, FTP, and HTML. All three
are easily accessed graphically through html web sites by URLs (uniform
record locators: gopher://, ftp:// and http://). The HTML page consists
of combined text, graphic, and audio files within a structure of TITLE,
HEAD, and BODY. These files are transferred to the user's computer where
the interpreted file is displayed by the user's Internet browser.
The capabilities of the browsers vary greatly, with advancements far out
pacing standardization. All browsers are capable of transferring text information
and graphics files, advanced browsers host conferencing, display full animation
and sound, and can act as the primary desktop for personal computing.
Several web sites now include identification keys with graphical information,
but the potential for collaboration is far from fully recognized. Conceivably,
within the next few years, a global database of illustrations and descriptions
will be seamlessly integrated on the Internet, permitting rapid identification
of modern and fossil palynomorphs.
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SEICHES IN LAKE ERIE - PALYNOLOGICAL EVIDENCE
Stephen Douglas1, Francine McCarthy2, and Steve Blasco3
1Department of Earth Science, University of Waterloo, Waterloo, Ontario,
Canada, N2L 3G1
2Department of Earth Sciences, Brock University, St. Catharines, Ontario,
Canada, L2S 3A1
3Geological Survey of Canada - Atlantic, Bedford Institute of Oceanography,
Dartmouth Nova Scotia, Canada, B2Y 4A2
Seiches result from wind setups and storm surges and are characterized
by high water levels at the downwind end of a body of water. The configuration
of Lake Erie with its long axis parallel to major storm tracks across the
Great Lakes region, along with a narrowing of the lake at the eastern end,
tends to focus strom surges, making seiches relatively common in eastern
Lake Erie and a concern for property owners.
Palynological evidence at Core 10, in 50 m of water south of Long Point,
indicates low rates of sedimentation since ~3,600 y BP. Undulations of the
lake bed, and winnowing and deposition around a shipwreck located near the
site, indicate current activity and erosion well below wave base. The low
percentages of small, light pollen grains such as Ambrosia and the relatively
large percentages of more resistant taxa such as Acer saccharum both on
and immediately adjacent to the shipwreck indicate the possible reworking
of sediments. We hypothesise that strong, episodic bottom currents caused
by oscillatory or return flow during seiches interact with the sediments.
Strong bottom currents are only recorded in sediments after 3,600 y BP and
may result from progradation of Long Point into the deep eastern basin after
the Nipissing `Flood', which may act as a focus for such currents.
Palynological and sedimentological evidence suggests that Core PTA2, taken
from a forested swamp 3 m above the current water level of Lake Erie, became
an isolated peat basin after the Nipissing `Flood' water levels receded
~3,600 y BP. A zone of fluctuating aquatic and terrestrial pollen taxa,
bracketed by radiocarbon dates, indicates a reintroduction of Lake Erie
water to the study site between 3,000 to 2,900 y BP, probably caused by
seiches. A series of sand ridges that currently separate the peat basin
from Lake Erie suggest that Lake Erie water levels must have been close
to 176 m asl in order for the incursion of fresh water to take place at
the site, suggesting that the Lyell/Johnson sill continued to control the
level of Lake Erie until 2,900 y BP. The switch of controlling sills for
Lake Erie to the Fort Erie/Buffalo sill may have therefore taken place at
a later date than previously reported.
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EVOLUTION, MIGRATION, AND TAXONOMIC UNCERTAINTY: DINOCYSTS FROM THE MIOCENE
IN SOUTHERN FLORIDA
Lucy E. Edwards1 and Kathleen R. Simmons2
1U.S. Geological Survey, 926A National Center, Reston, Virginia 20192,
U.S.A.
2U.S. Geological Survey, P.O. Box 25046, MS 980, Denver, Colorado 80225,
U.S.A.
A deep core hole (GB-1) from southern Florida provides 176 m (almost
600 feet) of early and middle Miocene sediments. High-resolution strontium-isotopic
data from mollusk shell material indicate virtually continuous deposition
from 22 to 13 Ma with a nearly uniform sedimentation rate around 20 m/m.y.
All samples from the shallow marine carbonate sediments contain the warm-water,
neritic forms Spiniferites spp., Polysphaeridium zoharyi, Lingulodinium
machaerophorum, and Operculodinium spp. Nearly all also contain Dapsilidinium
pseudocolligerum, Systematophora placacantha, Tuberculodinium vancampoae,
and Sumatradinium spp. Most samples are dominated by Spiniferites, but with
significant P. zoharyi; a few are dominated by P. zoharyi.
Dinocysts from the GB-1 core can be compared with Miocene material from
the middle Atlantic Coastal Plain reported by de Verteuil and Norris (1996).
Although only some of their marker species are present, the dinocysts and
the strontium-isotope data indicate correlation with their zones DN 2 through
DN 5.
Based on strontium-isotope stratigraphy, the earliest occurrence of Labyrinthodinium
truncatum may be 2 m.y. earlier in southern Florida than in the middle Atlantic
Coastal Plain. In both locations, the species shows early sporadic occurrences
below consistent presence. Migration and ecology, rather than evolution,
may determine its first occurrence. In contrast, the lowest occurrence of
Habibacysta tectata appears to be a good correlation horizon in both areas,
at about 14 Ma.
The ranges of several species are shortened in the GB-1 core relative to
reported worldwide or Atlantic Coastal Plain ranges. Hystrichosphaeropsis
obscura, Spiniferites mirabilis, Melitasphaeridium choanophorum, Selenopemphix
brevispinosa, and Batiacasphaera sphaerica all have their lowest occurrences
higher in the lower Miocene or middle Miocene than previously reported.
These species are relatively rare in most of the Florida samples. The highest
occurrence of the Pentadinium complex in the lower Miocene reflects the
range of the single species rather whereas higher ranges worldwide most
likely reflect the ranges of additional taxonomic entities that could be
separated for increased stratigraphic resolution.
The reported ranges of Trinovantedinium papulum, Cribroperidinium tenuitabulatum,
and Apteodinium tectatum are extended by the GB-1 core. Cribroperidinium
tenuitabulatum, therefore, may not be an indicator of cooler and more offshore
conditions, as has been previously speculated.
The high-resolution stratigraphy of the GB-1 core provides a means for assessing
environmental preferences and the timing of dispersal of Miocene dinocyst
species.
Reference:
DE VERTEUIL, L., AND NORRIS, G. 1996 Miocene dinoflagellate stratigraphy
and systematics of Maryland and Virginia. Micropaleontology, v. 42, suppl.,
p. 1-172.
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HYDROSTRATIGRAPHIC CORRELATION USING PALYNOLOGY AND PALEOENVIRONMENTAL ANALYSES:
AN ONGOING STUDY AT THE SAVANNAH RIVER SITE, SOUTH CAROLINA
Engelhardt, Donald W.1, Raymond A. Christopher2 and Robert S. Van Pelt3
1Earth Sciences and Resources Institute, University of South Carolina,
Columbia, South Carolina 29208, U.S.A.
2Department of Geological Sciences, Clemson University, Clemson, South Carolina
29634-1908, U.S.A.
3Bechtel Savannah River Company, Aiken, South Carolina 29808, U.S.A.
At the Savannah River Site in South Carolina, characterizing the nature,
extent, and stratigraphic relationships of subsurface units is an integral
part of ongoing environmental restoration efforts. Palynology is used to
assist in interpretation of hydrostratigraphic units and depositional environments
in the subsurface. Palynologically based biostratigraphy and paleoenvironmental
interpretations provide refined hydrostratigraphic correlation. Palynofacies
(organic sedimentary particles derived from marine and terrestrial environments)
and dinoflagellate species diversity are used to characterize various lithofacies
and document the transgression and regression of depositional environments
in response to changes in sea level. These features, in turn, can serve
as preferential pathways for groundwater movement.
Categories of palynofacies include amorphous, inertinite, plant fragments,
leaf cuticle, dinoflagellates/acritarchs, pollen and spores, microforaminifera
linings and fungi. These types are representative of fluvial/swamp through
open marine shelf environments.
The results of an analysis of Upper Cretaceous through Eocene sediments
in selected wells demonstrate the effectiveness of integrating multiple
data sets in the interpretation of the complex hydrostratigraphy of the
South Carolina Coastal Plain.
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DINOFLAGELLATES: NOW AND THEN
R. A. Fensome1, R. A. MacRae1, G. W. Saunders2, F. J. R. Taylor2 and G. L. Williams1
1Geological Survey of Canada - Atlantic, Bedford Institute of Oceanography,
Dartmouth, Nova Scotia, B2Y 4A2, Canada
2Department of Oceanography, University of British Columbia, Vancouver,
British Columbia, V6T 1Z4, Canada
The extant and fossil records of dinoflagellates provide complementary
evidence in unravelling the evolutionary history of the group. Extant dinoflagellates
provide information through comparative anatomic and molecular phylogenetic
studies, and both types of study point to an ancient divergence of the dinoflagellate/apicomplexan/ciliate
("alveolate") lineage from the chromophyte lineage (including
diatoms and chrysomonads). The timing of the separation of the dinoflagellate
line from other alveolate lines is uncertain, although the molecular phylogenetic
data points to a very close relationship between the dinoflagellates and
apicocomplexans.
The pre-Mesozoic fossil record of dinoflagellates is also not very helpful
in determining the timing of the origin of dinoflagellates. Arpylorus, from
the Silurian, has been viewed by many as a dinoflagellate, and its multiplated
wall structure certainly supports an alveolate affinity. However, claims
that the morphology of Arpylorus reflects flagellar furrows are not completely
convincing. Nor are the claims of affinity for other supposed pre-Mesozoic
dinoflagellates.
From the Late Triassic, however, the story is different. Dinoflagellate
cysts appear with generally increasing diversity (i.e. species richness)
into the Cretaceous. Many of these cysts reflect clear evidence of flagellar
furrows and variations on modern tabulation patterns. The relatively sudden
blossoming of dinoflagellates in the early Mesozoic was believed by some
to have been an artefact of the fossil record, involving the development
of fossilizable cysts in different lineages. However, we now consider that
this diversification episode represents a true evolutionary radiation. The
early "experimentation" with a variety of morphologies and the
subsequent stabilization of several persistent lineages within the group,
for example the Gonyaulacales and Peridiniales, support this idea.
The diversity (i.e. species richness) curve of fossil dinoflagellate cyst
species per unit time since the Triassic is broadly hump-shaped. It shows
peaks in the Kimmeridgian, Albian, Maastrichtian (the all-time high) and
Early Eocene, before declining to the Pliocene. The incomplete nature of
the dinoflagellate fossil record and the pattern of number of publications
per unit time add caveats to this data. However, we believe that the pattern
also relates in part to the long-term sea-level curve and global climates.
The evolutionary history of the dinoflagellates is a fascinating study,
involving not just comparative anatomy, molecular phylogenetics and the
fossil record, but also topics such as biogeochemistry and paleogeography.
Many questions remain. For example, were flagellar furrows "invented"
during the early Mesozoic radiation? Are modern peridinialeans more varied
in their tabulation patterns than fossil ones, as suggested by the respective
thecal and cyst records and, if so, why? Did Triassic dinoflagellates co-evolve
with scleractinian corals, as circumstantial evidence tantalizingly hints
at? What can Quaternary dinoflagellate diversity curves tell us about global
change? These questions and others are fuel for ongoing research.
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LARGE ACANTHOMORPHIC ACRITARCHS: THEIR EVOLUTION, DIVERSIFICATION AND EXTINCTION
ACROSS THE NEOPROTEROZOIC - A CASE HISTORY FROM THE KROL FORMATION, LESSER
HIMALAYA, INDIA
Rajita Gautam1 and Vibhuti Rai1
1Department of Geology, University of Lucknow, Lucknow, India
The Neoproterozoic time span encompassing about 460 million years of
Earth history occurs as a transitional period representing the feebly developed
biota of the Proterozoic and the sudden explosion of life during the Phanerozoic.
Various physical and chemical changes occurred during this period which
affected the evolution of the biotic community. Of these, the evolution
of phytoplankton with its abrupt and index changes during the terminal Proterozoic
is of great significance. The phyutoplankton community of the Neoproterozoic
Krol Formation is well represented by acritarchs. The thin-section study
of bedded black cherts, interlayered within shallow marine carbonate deposits,
from the Krol 'A' Member of the Krol Formation has yielded an exceptionally
well preserved silicified microbial assemblage form the Himalayan successions.
The assemblage comprises planktic as well as benthic, mat-building, colonial
and solitary forms of cyanobacteria and other algal groups. Confirmed occurrences
of eukaryotic algae and acritarchs are also recorded. The acritarchs range
from small- to large-sized vesicles, simple sphaeromorphic to highly ornamented
acantho-morphic forms.
The large acanthomorphic acritarchs occur mainly as collapsed and compressed
vesicles with some robust forms preserved in-toto, clearly showing their
morphological details. A remarkabel increase in taxonomic diversity as well
as in the number of these forms denotes the evolutionary changes that occurred
during this time. The adaptation of acritarchs to these evolutionary changes
and newly evolved ecological niches is also reflected in the increased size
(gigantism) and process morphologies, which range from simple to complex
variations of conical, spiny and hairy types. Some of the larger forms have
been identified as Ericiasphaera, Ap[pendisphaera, Asterocapsoides, and
Baltisphaeridium. However, a majority of the acritarchs are unique to the
assemblage as they do not show any resemblance to the known existing forms.
The evolutionary pattern of these acritarchs can be traced along the sequence
where an increase in the size, number and morphology is seen from the lower
horizons of the Krol 'A' Member with a gradual decrease towards the top
of the succession in the loermost part of the overlying Tal Formation. The
occurrence and evolutionary significance of these previously unrecorded
forms which form an important component of the microplanktonic community
of the Neoproterozoic Himalayan successions is discussed in this paper.
___________________________________________
AN APPLIED INTEGRATED APPROACH (PALYNOLOGY, MICROPALAEONTOLOGY, AND STRUCTURAL
RESTORATION) TO OCEANIC/SHALLOW MARINE ECOSYSTEMS OF OFFSHORE NORWAY.
Gavin K. Gillmore1,2, Tomas Kjennerud1 and Eric Monteil1
1IKU Petroleum Research, N-7034 Trondheim, Norway
2Nene College of Higher Education, School of Environmental Science, Earth
Science, Park Campus, Boughton Green Road, Northampton, Northamptonshire,
NN2 7AL, United Kingdom
Until now, available data relative to palaeowater depths has been poorly
documented. Generally, authors cite water depths for species/genera with
little or no support for their conclusions, or give no clear indication
on what their conclusions are based. Typically, a very subjective approach
is adopted, and workers in this field often support palaeowater depth estimates
on their own (and more rarely others) experience rather than on a particular
methodology. The aim of this research is to develop a methodology in palaeowater
depth assessment that is objective and reproducible.
In order to carry out this research, an integrated approach to palaeobathymetry
using micro-palaeontology (foraminifera, radiolaria, and diatoms), palynology
(dinoflagellates and palynofacies), and structural restoration techniques
is adopted. This approach delineates palaeobathymetric trends and assesses
lateral faunal and floral changes along shelf to basin transects. Palaeowater
depth is fundamental to basin modelling, but is probably the hardest parameter
to measure. This is because few sedimentological criteria are controlled
precisely by water depth. Most organisms which show a so called depth-related
distribution are, in fact, controlled by an interaction of multiple factors.
Foraminiferal assemblages have been widely used for palaeoenvironmental
interpretations in the Mesozoic and Cenozoic, and a limited number of palaeobathymetric
models have been proposed for Cretaceous sediments. The use of dinoflagellate
cysts in palaeoenvironmental reconstruction is a recent approach, and only
a few sophisticated palaeo-environmental models have been proposed for the
Tertiary.
The depth distribution of foraminifera is a function of several interacting
factors, such as temperature, salinity, oxygen levels, nutrients, and the
nature of the substrate. The depth distribution of dinoflagellate cysts,
however, is more complex. In modern oceans, distribution of the planktonic
stage of dinoflagellates is largely a function of temperature, salinity,
and distance from the coast. Absolute abundance, or productivity, is dependent
on light, salinity, temperature, nutrient supply, oxygen levels, and current
conditions. On a global scale, the distribution of motile dinoflagellates
is basinwards-landwards and oceanic-climatic. The distribution of cysts
is dependent on several factors, including distribution of motile stage
species, biological and ecological controls over encystment, and the behaviour
of cysts as sedimentary particles in the hydrographic regime. Over and above
this, the distribution of sedimentary organic particles, and thus distribution
of dinoflagellate cysts in sediments, are also highly influenced by the
change in stacking patterns of depositional systems (LST, TST or HST).
This unified micropalaeontological and palynological approach is combined
with a new structural restoration technique. The latter modifies the traditional
structural restoration method to take into account palaeobathymetry in an
extensional regime (using simple shear as a deformation mechanism). Based
on depth converted and interpreted seismic sections, a relative relief is
restored for each timestep taking into account the geometries of the seismic
sequences. In some cases when the conditions are favourable (laterally uniform
subsidence, pin points such as coal horizons and prograding clinoforms that
can be measured), these relative profiles can become close approximations
to absolute ones.
This integrated approach enables the identification of likely palaeowater
depths based on upper depth limits provided by foraminiferal and palynological
studies and the deepest likely scenario obtained from the geometry of seismic
sequences. By combining the palaeowater depth ranges derived from micropalaeontology
and palynology studies, with angles obtained from the seismic sequence under
study, angular ranges for the studied time slice and associated sediments
between at least two wells, can be used to constrain palaeodepth estimates.
Accurate assessment of palaeobathymetry is important in predicting the distribution
of sediments and burial history, source rock stratigraphy, and source rock
potential. This combined approach also gives better control on the evolution
of reservoir rocks through time (hydrocarbon migration pathways).
___________________________________________
THE GLOBAL POLLEN DATABASE
Eric C. Grimm1 and John Keltner 2
1Illinois State Museum, Research and Collections, 1011 East Ash St.,
Springfield, Illinois 62703, U.S.A.
2NOAA Paleoclimatology Program, 325 Broadway E/GCx3, Boulder, Colorado 80303,
U.S.A.
The global Pollen Database (GPD) contains Quaternary pollen data from
the Americas, Europe, Africa, northern Asia, and the Indo-Pacific region.
New data are organized and made available by various regional data cooperatives.
The GPD began with the development in 1990 of the independent but compatible
North American and European Pollen Databases (NAPD and EPD). The GPD was
conceived in 1994 with the development of the Latin American Pollen Database,
which was integrated with NAPD from the outset. Beginning in 1997, the GPD
has incorporated date from the Indo-Pacific Pollen Database and non-restricted
data from the EPD.
The objective of the GPD is to assemble pollen data for Quaternary deposits
and modern surface samples into a relational database and to make these
data readily available to the scientific community. The database contains
original pollen counts, radiocarbon dates, site data, bibliographic data,
worker information, and other relevant data.
The database makes an important distinction between archival data and research
data. Archival tables store the count data, radiocarbon dates as reported
by the radiocarbon laboratories, and other basic data not expected to change,
except to add missing information or correct errors. Research tables store
data that are derived by manipulation of the archival tables and are of
an interpretive or subjective nature. Probably the most important of the
research tables are those containing age models and chronologies, including
the assignment of an age to each pollen sample.
The GPD is available from the World Data Center-A for Paleoclimatology,
which is housed at the National Geophysical Data Center in Boulder, Colorado.
In addition to the database tables themselves, that data are available in
several file formats via the World Wide Web (http://www. ngdc.noaa.gov/paleo/pollen.html)
and anonymous FTP (Ftp.ngdc. noaa.gov in/paleo/pollen).
___________________________________________
REWORKED DINOCYSTS AS A MEANS OF OBTAINING USEFUL GEOLOGICAL INFORMATION.
A CASE STUDY OF THE UPPER JURASSIC DRAUPNE FORMATION IN THE TAMPEN AREA,
NORWEGIAN NORTH SEA
Kjell-Owe Häger1 and Morten Smelror2,3
1Norsk Hydro Research Centre, N-5020 Bergen, Norway
2IKU Petroleum Research, N-7034 Trondheim, Norway
3Present address: NTNU Museum of Natural History and Archaeology, N 7004
Trondheim, Norway
This paper presents a study of reworked dinocysts within an Upper Jurassic
succession in the Tampen Spur area, Norwegian North Sea (Block 34/7). The
study area comprises the flanks of a rotated fault block (Snorre H), forming
a half-graven dipping to the west-southwest. The crest of the fault block
to the east and north has been significantly eroded in the course of Late
Jurassic rifting and block rotation episodes. The sediments studied consist
of sands and shales deposited as syn-rift wedges on the dip-slope of the
fault block. Palynological analyses were performed on five wells (34/7-21,
-21A, -23S, -23A and -24S) which, togethere with available reports, were
used to establish a palynozonation before identifying the reworked dinocysts
within each zone.
The observed patterns of reworking, together with conventional zonation
and age determination, were then used as an aid in interpreting sedimentary
conditions and tectonic development of the half-graben and its flanks, i.e.,
by identifying eroded successions and as an indication of timing of the
block rotation. A short review of methodology and principles regarding the
study of reworked palynomorphs in general is also presented. The main results
of this study can be summarized as follows:
€Reworking indicates that two, or possibly three periods of increased
sediment transport into the Snorre H half-graben - one in late Oxfordian/
Kimmeridgian times, one in the Late Volgian/-Ryazanian and one possibly
also during the Early-Mid Volgian.
€The first indication of erosion of Brent sediments appears around
the Callovian/Oxfordian boundary, indicating that before this time sand
sources in the area were limited.
€ A presentation style for reworking data is proposed that elucidates
the important relationships between strata of origin and strata of deposition.
Other studies in the area, including sedimentary core descriptions as
well as seismic and structural interpretations, have been used to calibrate
the above results but are not described in detail in this report. It is
concluded that an analysis of reworking may serve as a supplementary tool
in constructing and validating geological models. There is probably also
considerable potential for improving and facilitating the study of reworked
material by using computerized tools for the definition and analysis of
in situ and reworked taxa.
___________________________________________
MODERN DINOFLAGELLATE CYSTS IN A TRANSECT FROM THE FALKLAND TROUGH TO THE
WEDDELL SEA, ANTARCTICA
Rex Harland1, Carol J. Pudsey2, John A. Howe2 and Meriel E. J. FitzPatrick3
1DinoData Services, 50 Long Acre, Bingham, Nottingham NG13 8AH, United
Kingdom, and Centre for Palynology, University of Sheffield, Mappin Street,
Sheffield S1 3JD, United Kingdom
2British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET,
United Kingdom
3Department of Geological Sciences, University of Plymouth, Drake Circus,
Plymouth PL4 8AA, United Kingdom
Dinoflagellate cyst analysis has been completed on core-top samples that
form a transect from near the Falkland Islands south to the Weddell Sea,
Antarctica. This study is the first to document the distribution of the
modern dinoflagellate cyst thanatocoenosis in the area.
Seventeen dinoflagellate cyst taxa were identified and at least two species,
Dalella chathamense McMinn & Sun and Selenopemphix antarctica Marret & de
Vernal, are recognised as endemic to the Southern Hemisphere from the results
of this study and from previously published research. Data presented reveal
a clear latitudinal trend in the cyst distribution such that a subdivision
into two domains is possible. The first, to the south of 60°S, is characterised
by low numbers of cysts, low diversity and the presence of Impagidinium
pallidum Bujak, Algidasphaeridium? minutum (Harland & Reid) Matsuoka & Bujak,
Pentapharsodinium dalei Indelicato & Loeblich III, round brown Protoperidinium
cysts and Selenopemphix antarctica. The second, to the north of 60oS, is
characterised by richer assemblages, higher species diversity and the presence
of Dalella chathamense, Impagidinium sphaericum (Wall) Lentin & Williams,
Nematosphaeropsis labyrinthus (Ostenfeld) Reid and high numbers of Selenopemphix
antarctica.
This division of the cyst assemblages coincides approximately with the northern
winter limit of sea-ice, an important constraint on the amount of light
available for primary production. In addition we recognise that the increase
in cyst diversity and numbers north of 60oS is largely due to an increase
in cysts attributable to the cyst genus Protoperidinium. These motile forms
are heterotrophic and are feeding on the rich diatom populations that are
enjoying the increased nutrient content of the famous upwelling region of
the Antarctic.
Clearly various aspects of the dinoflagellate cyst analysis demonstrates
their potential to elucidate the palaeoceanography of the region and offers
a means to explore climate change by identifying, with confidence, biogeographical
boundaries that can be traced through the recent fossil record.
___________________________________________
NEW GONIODOMACEAN DINOFLAGELLATES WITH A HYPOCYSTAL ARCHEOPYLE FROM THE
PLIOCENE OF THE NORTH ATLANTIC.
Martin J. Head
Department of Geology, Earth Sciences Centre, University of Toronto, Toronto, Ontario, Canada, M5S 3B1
A new goniodomacean dinoflagellate genus of the subfamily Pyrodinioideae,
whose archeopyle results exclusively from dissociation of hypocystal plates,
is described from the late early Pliocene Coralline Crag Formation of eastern
England and the late Pliocene and possible earliest Pleistocene of the Clino
Core, western margin of the Great Bahama Bank. The genus is represented
by two new species, and provides the only unambiguous example of a hypocystal
archeopyle in the order Gonyaulacales.
Cysts are thin-walled, spherical and proximate, and have a loose diaphanous
outer layer. Pre-formed lines of weakness occur exclusively on the hypocyst,
where they follow plate boundaries. Upon excystment, these sutures facilitate
the individual and more-or-less simultaneous release of plates 1-5''', ps,
1p, and 1''''. Sulcal plates ls, rs, and las (first postcingular homologue)
typically remain attached to the epicyst, forming a unique hyposulcal tab.
These unusual dinoflagellates thrived, and perhaps formed blooms, in warm-temperate,
carbonate shelf environments of the Bahamas during the late Pliocene, and
might be a useful marker for warm-temperate intervals within the Pliocene
of the southern North Sea.
Why are hypocystal archeopyles so rare in the dinoflagellate record? The
near exclusive restriction of archeopyles to the epicyst, evolutionary conservatism
of hypocystal tabulation, and forward swimming of the motile stage are suggested
as being mutually linked characters in dinoflagellate evolution.
___________________________________________
CRETACEOUS - TERTIARY STRATIGRAPHY AND DINOFLAGELLATES FROM
BAJA CALIFORNIA
Javier Helenes
CICESE, Departamento de Geologia, Km. 107 Carretera Tijuana-Ensenada,
Ensenada, Baja California 22860, Mexico.
Postal Address: P. O. Box 434843, San Diego, California 92143-4843, U.S.A.
A sedimentary sequence ranging in age from Valanginian (?) to middle
Eocene is present in the western side of the Baja California Peninsula.
The lowermost unit was deposited in an island arc setting. It is composed
mainly of volcaniclastic strata, and overlies a Jurassic to Early Cretaceous
igneous basement. Near the top of the unit, reefal limestones are present,
and they contain abundant rudists and nerineans. These limestones also contain
a diverse dinoflagellate assemblage dominated by chorate gonyaulacoid taxa,
and the species Ascodinium diversum, Cribroperidinium auctificum, Subtilisphaera
zawia, Cribroperidinium intricatum, and Cribroperidinium grande, indicating
a late Albian age.
Overlying this unit, an almost continuous Late Cretaceous to Early Tertiary
sedimentary wedge has yielded planktonic foraminifera and dinoflagellates
indicating ages from Cenomanian to middle Eocene. Nearshore facies of these
units indicate at least two major transgressive cycles in the Late Cretaceous
interval, and one in the Paleocene. Rich dinoflagellate assemblages have
been recovered from the Maastrichtian, early Paleocene and middle Eocene
intervals. The Maastrichtian assemblages contain more peridinioid taxa than
the Albian assemblages, but also include the species Xenascus ceratioides,
Dinogymnium acuminatum, Spiniferites fluens, and Palaeocystodinium benjaminii.
The early Paleocene assemblage contains slightly more peridinioid than gonyaulacoid
forms, and includes the species Senegalinium obscurum, Impagidinium pentahedrias,
Damassadinium californicum, Alisocyta circumtabulata, and Duosphaeridium
rugosum. The middle Eocene assemblage contains mainly chorate gonyaulacoid
forms and very few peridinioids. Common species are: Areosphaeridium arcuatum,
Achilleodinium biformoides, Hystrichostrogylon membraniphorum, Microdinium
reticulatum, and Impagidinium californiense.
___________________________________________
MEXICAN CORN ROOTWORMS, COCKROACHES OF THE CORNFIELDS
G. D. Jones1 and J. R. Coppedge1
1USDA, ARS, Areawide Pest Management Research Unit, 2771 F & B Road., College Station, Texas 77845, U.S.A. e-mail: g-jones@tamu.edu
The Mexican corn rootworm (Diabrotica virgifera zeae Krysan & Smith)
is an insect pest that attacks corn. Adults feed on corn leaves, silks,
pollen, and immature seeds while the larval stage feeds on corn roots. Historically,
corn rootworm management has been accomplished by application of soil application
insecticides at planting and by rotation of corn with a non-susceptible
crop. Soil insecticides often are used regardless of the level of rootworm
infestation, and do not always control the larval stage. In recent years,
crop rotation has not completely prevented corn rootworm infestations in
corn. Because adults can fly from field to filed, controlling the adult
stage is difficult. For the last several years, the USDA Areawide Pest Management
Research Unit has been conducting research to control adult corn rootworms.
As part of this research, it was important to determine if Mexican corn
rootworm adults foraged on plants other than corn.
Adult Mexican corn rootworms, captured near Temple, Texas, in May and June,
1996, were analyzed for pollen to determine foraging resources. Seventy-four
percent (74%) of the samples contained pollen. A total of 1,823 pollen grains
and 48 pollen types were found in the samples. Pollen representing 26 families,
26 genera, and five species were identified. Mexican corn rootworm adults
captured in May foraged on more pollen types (40), plant families (21),
genera (24), and species (3) than those captured in June. However, the majority
of pollen grains encountered were in June samples. Corn, Zea mays Linnaeus,
pollen accounted for more than 86% of the Poaceae grains in June. Mexican
corn rootworm adults foraged on the fewest alternative foraging resources
in June. Our research suggests that Mexican corn rootworm adults have a
wide range of foraging resources. The diversity of foraging resources indicates
that adults can be sustained by pollen prior to corn silking, and move in
and out of cornfields.
___________________________________________
WE'RE TIRED OF CORN, BRING ON THE SOYBEANS
Gretchen D. Jones1, James R. Coppedge1, Ester F. Wilson1 and Larry D. Chandler2
1USDA, ARS, Areawide Pest Management Research Unit, 2771 F & B Road.,
College Station, Texas 77845, U.S.A. e-mail: g-jones@tamu.edu
2USDA, ARS, Northern Grain Insects Research Laboratory, R. R. 3, Brookings,
South Dakota 57006, U.S.A.
Western corn rootworms (Diabrotica virgifera virgifera Le Conte) are
serious insect pests of corn (Zea mays Linnaeus). Female beetles lay eggs
in the soil of cornfields. Eggs remain dormant until the next spring, when
they hatch. The larval stage feeds on corn roots. Damage to roots weakens
the plant by reducing its ability to absorb water and nutrients. Often the
weakened root system can no longer support the plant and the plant falls
over. Soil insecticides applied to kill larvae and protect roots cost approximately
$37 million yearly in Illinois alone. To disrupt the beetles' life cycle,
corn is alternated yearly with unsuitable host crops, such as soybean [Glycine
max (Linnaeus) E. Merrill].
In the early 1990s, corn rootworm damage was reported in Illinois and Indiana
corn fields that were previously planted with soybeans. It was speculated
that eggs remained dormant for several years until corn was planted again.
However, there are recent reports of adult movement into and egg laying
in soybean fields. The purpose of this research was to determine if western
corn rootworms moved into and foraged on soybeans.
One hundred and ninety (190) western corn rootworm adults captured in July
and August, 996, near Thomasboro, Illinois, were examined for pollen. A
total of 502 pollen grains, 30 pollen types, and two vascular spore types
were found in the samples. Pollen representing 15 families, 11 genera, and
two species were identified in the samples.
More than half (305) of the 502 pollen grains were soybean, and 92 were
corn. Soybean pollen first appeared in the August samples and remained present
throughout August. Although corn pollen was found throughout the study,
its numbers were reduced in August. Our research shows that western corn
rootworm adults were in soybean fields in August and fed on soybean pollen
during that time.
___________________________________________
LIFE IN THE PRECAMBRIAN OCEANS: EVIDENCE AND QUESTIONS
Andrew H. Knoll
Botanical Museum, Harvard University, Cambridge, Massachusetts 02138, U.S.A.
We know, and have known for decades, that Phanerozoic ecosystems were
preceded by a long interval of Precambrian evolution. The biology of Archean
oceans remains poorly constrained, but in recent years, taxonomic, paleoenvironmental,
and stratigraphic patterns have emerged that enable us to approach the Proterozoic
fossil record in a predictive fashion that looks to generalizations about
early life.
Cyanobacteria are among the most morphologically diverse and developmentally
complex of all eubacteria, making them one bacterial clade for which morphology
provides useful systematic characters. Cyanobacteria were widely distributed
in Proterozoic environments favoring fossil preservation, and were of paramount
ecological and biogeochemical importance on the early Earth. Even shallow
branches of the cyanobacterial tree, including the heterocyst-bearing Nostocales,
are represented in fossil assemblages 2100 Ma or older, indicating that
much cyanobacterial diversification occurred during the Archean or earliest
Proterozoic Eon. Eukaryotes are represented in Proterozoic rocks by both
morphological and biomarker remains. Simple microfossils and steranes of
probable eukaryotic origin can be traced back to 1,800 Ma and possibly as
far as 2,450 Ma; however, there is little evidence for pronounced algal
diversification until 1,200-1,000 Ma, when green, red, and chromophyte algae
first appear in the rock record.
If the distribution of Proterozoic fossils in time and space is becoming
better known, fundamental questions remain about the ecological structure
and productivity of early oceans. It is tempting to address such issues
by starting with current ecosystems and subtracting from them those components
known to have evolved during the Phanerozoic Eon; however, the prevalence
of non-linear responses in ecology discourages overreliance on this approach.
Important constraints are likely to emerge from rapidly improving biogeochemical
data on Proterozoic ocean basins, but such studies, however promising, are
in their infancy.
___________________________________________
ANALYTICAL TOOLS FOR USE WITH PARADOX-BASED POLLEN DATABASES
Phillip L. Leduc1, John W. Williams1 and Thompson Webb III1
Department of Geosciences, Brown University, Providence, Rhode Island
02912, U.S.A.
email: phillip_leduc@brown.edu, jww@brown.edu, thompson_webb_iii@brown.edu
The assembling of regional and global pollen databases did not begin
with the invention of the Internet, but the Internet makes it much easier
for palynologists around the world to access these data warehouses. Current
on-line databases, most of which are maintained by the NOAA Paleoclimatology
Program, include
the North American Pollen Database (NAPD) (http://www.ngdc.noaa.gov/paleo/napd.html),
Global Pollen Database
(http://www.ngdc.noaa./paleo/gpd.html),
European Pollen Database
(http://www.ngdc.noaa.gov/paleo/epd.html),
African Pollen Database, and Latin American Pollen Database (http://www.ngdc.noaa.gov/paleo/lapd.html)
with others under construction. The databases are continually maintained
and updated, and offer data that has been quality checked and is in standardized
formats. But ease of access is not the same as ease of use: one of the great
problems posed by this wealth of data is the need for programs that can
search and manipulate the databases. At Brown University, we work extensively
with the NAPD, and have developed a tool kit, called PATools (this stands
for Pollen Analysis Tools) to aid paleovegetation reconstructions.
A major difficulty for would-be users of the NAPD is that it is not a single
data table (this would be far too unwieldy), but instead consists of many
tables, complexly linked together. PATools is a collection of Paradox tools
developed over the last three years at Brown University that enables analysts
to extract information from the NAPD via a graphic user interface of drop-down
menus and pushbuttons. Although PATools has been developed for use with
the NAPD, it could be adapted to other pollen databases of similar structure.
A user of PATools first chooses the pollen types for display, the pollen
sum, and the sites for study. Sites can be selected by latitude and longitude,
political division, age, and/or type of record (core vs. section vs. surface
sample). When these selections are complete, PATools gathers the relevant
information from the NAPD and dynamically builds pollen count and percent
tables and can interpolate between pollen samples to produce data for specific
timeslices. Pollen counts, percentages and interpolated percentages with
supplementary site and chronology information can be printed as individual
site reports. PATools will identify which sites have incomplete data (e.g.
are missing a chronology) and can produce a report listing such sites and
their data gaps. PATools can convert radiocarbon dates into calendar years
for the past 50,000 rka, and is fully usable in either form. PATools allows
the user to analyze a site's chronology by ranking chronology quality, i.e.
the number and proximity of bracketing dates for a given timeslice, and
by allowing an analyst to experiment with modifying chronologies by use
of an interface that instantly shows the effects of adding or removing dates
upon pollen sample ages. We recently added an analogue capability to PATools,
allowing PATools to search a pollen database for closest analogues to a
given pollen sample or timeslice. The user can select from six measures
of dissimilarity and can accept the default threshold values or use his
or her own. PATools has several utility tools, including the ability to
compare tables, number records or samples within a table, and convert between
pseudo-decimal and decimal latitude/longitude formats.
A few disclaimers: PATools is written for Paradox 7 (the database manager
used by NAPD), so users must have this software before they can make use
of the tools. PATools works within the Paradox 7 environment, so does not
relieve the user of the need to have some familiarity with the software.
We plan to make PATools publicly available but do not yet have a help feature,
nor is it yet documented. However, PATools is fairly intuitive to use.
___________________________________________
INTERNATIONAL QUATERNARY ASSOCIATION (INQUA) DATA-HANDLING METHODS AVAILABLE
FREE ON THE WORLD WIDE WEB
Louis J. Maher, Jr.
Department of Geology and Geophysics, University of Wisconsin, 1215 West Dayton St., Madison, Wisconsin 53706, U.S.A.
At the XIIth International Quaternary Association (INQUA) meeting in
Ottawa, 1987, Dr. Brigitta Ammann, President-elect of the Holocene Commission,
established a working group on data handling coordinated by R. C. Ritchie.
The group assembled a mailing list of colleagues interested in a continuing
flow of useful information on developments in computer and other technology
that help handle, exchange, analyze and otherwise deal with data more effectively.
The group produced a simple newsletter about twice a year that was distributed
internationally to more than 200 laboratories and individuals. At the XIV
INQUA meeting in Berlin, 1995, the Working Group was transformed to a Sub-Commission
on Data Handling Methods. J. C. Ritchie edited and coordinated the Newsletter
from June 1988 until January 1990, L. J. Maher served as editor from July
1990 until January 1997, at which time K. D. Bennett assumed that duty.
A small group of colleagues has served as an advisory panel: Keith Bennett,
John Birks, Rick Battarbee, Owen K. Davis, Lou Maher, and Jim Ritchie. These
and many others contributed to the Data-Handling Methods Newsletter over
the years, both as Working Group and Sub-Commission.
When data-handling methods were discussed, the Working Group always tried
to make the computer programs available so that others could try them out
with their own data. At first the programs were distributed on floppy disks,
but as the Internet became more accessible, text copies of the newsletters,
lists of mail/e-mail addresses, and self expanding zipped packages of computer
programs and sample data were kept in an anonymous ftp site at
With the advent of the World Wide Web, the File Boutique became a web site.
Its URL is
processing sample data from electronic balances, and global positioning
receivers. There are digital data from almost 300 Quaternary pollen sites,
and much more.
For those with slower transatlantic links an INQUA File Boutique mirror
site can be reached at
___________________________________________
POLLEN ANALYSIS AND PALEOCLIMATE OF THE "PORT MOODY INTERSTADE"
AROUND 18,000 YR BP IN COASTAL BRITISH COLUMBIA.
Rolf W. Mathewes
Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada, V5A lS6
The date of 18,000 14C yr BP (18ka) has long been used to define the
last global glacial maximum. There is good evidence that in the Pacific
Northwest, organic-rich sediments of the Sisters Creek Formation represent
the Port Moody Interstade (PMI), an interval of glacial retreat dated at
ca. 16-19 ka. Pollen analyses of PMI sediments were performed at five localities.
Abies and Picea dominate the arboreal pollen (AP), and NAP is composed mostly
of Cyperaceae, Poaceae, and Asteraceae. Indicator herbs of subalpine affinities,
such as Botrychium, Selaginella selaginoides, Bistorta, and Valeriana sitchensis
are also present. Pollen spectra from the five PMI sites were ordinated,
using detrended correspondence analysis (DCA) along with a set of coastal
surface samples. The PMI samples fall into a non-analogue space between
the coastal Mountain Hemlock zone and the interior Engelmann Spruce - Subalpine
Fir zones. Very low values for pine, and absence of alder pollen distinguish
the PMI samples from modern analogues.
When pollen and macrofossil data are combined, the PMI was a non-glacial
interval with subalpine climatic conditions, but with a growing season that
allowed the development of coniferous forest and associated vegetation suggesting
unexpectedly moist conditions around 18 ka.
___________________________________________
WHERE HAVE ALL THE SEDIMENTS GONE?
Francine McCarthy 1, Steve Blasco 2, David Dubas1 and Kevin Gostlin1
1Department of Earth Sciences, Brock University, St. Catharines, Ontario,
Canada, L2S 3A1
2Geological Survey of Canada - Atlantic, Bedford Institute of Oceanography,
Dartmouth, Nova Scotia, Canada, B2Y 4A2
Sediments on the lake bed in northern Georgian Bay are strongly dominated
by Pinus (both P. strobus and P. banksiana/resinosa), and contain little
herbaceous pollen (e.g., Ambrosia), Tsuga, or Fagus). The youngest sediments
recovered in piston cores were deposited > 6,500 years ago, i.e., prior
to the migration of Tsuga and most other thermophilous taxa to this region.
In contrast, sediments accumulated Rapidly ( up to ~ 4mm/y) in deep basins
between ~10,000 and 6,500 y BP, as rising lake levels recycled glacial Lake
Algonquin sediments (with sparse pollen recording ice-margin conditions,
e.g., Picea, Pinus, Cyperaceae, Pteridium). Lowstands within this interval
are marked by basin-wide erosional unconformities which were dated palynologically
and correlated with the Light Blue and Light Green events of Moore et al.
(1994).
Similarly, little sediment has accumulated in southeastern Georgian Bay
since the mid Holocene. In Severn Sound, a relatively thin (< 2m maximum
thickness) and spatially variable sedimentary unit containing Ambrosia and
other indicators of European settlement and landclearing appears to overlie
an older sedimentary unit marked by strong acoustic reflectors. Based on
the assemblages and state of preservation of palynomorphs in the upper acoustically
amorphous unit, we suggest that a relatively small volume of sediment has
been repeatly mixed and remobilized since the last lowstand in Severn Sound,
probably during the mid Holocene. The large thecamoebian populations dominated
by Curcurbitella tricuspis in the upper "mobile" unit are consistent
with low rates of accumulation of fine grained sediments in a relatively
warm, eutropic environment, while much smaller concentrations of thecamoebians
dominated by Difflugia oblonga and D. bacillifera within the older sedimentary
unit are consistent with deposition in a less productive (?colder) environment.
We attribute the sparse record of post-Nipissing sediments in Georgian Bay
to a sharp decrease in sediment influx with the cessation of transgression.
The very low rates of sediment accumulation anywhere in our study area (and
net erosion in some parts of Georgian Bay) have important implications for
environmental work in this basin.
___________________________________________
PALYNOLOGICAL SIGNATURE OF CONTI-NENTAL MARGIN SEQUENCES
Francine McCarthy1, Peta Mudie2, Kevin Gostlin1 and David Scott3
1Department of Earth Sciences, Brock University, St. Catherines, Ontario,
Canada, L2S 3A1
2Geological Survey Canada - Atlantic, Bedford Institute of Oceanography,
Box 1006, Dartmouth, Nova Scotia, Canada, B2Y 4A2
3Centre for Marine Geology, Dalhousie University, Halifax, Nova Scotia,
Canada, B3H 4A2
Ratios of contemporary pollen + terrestrial spores to dinoflagellate
cysts (P:D) were studied in well-dated (by magneto-, bio- and oxygen isotopic
chronologies) deep-sea cores of Miocene through Quaternary age. Major variations
in these P:D ratios indicate cyclical pulses of increased terrigenous organic
sediment influx to the deep sea, starting ~ 2.4 Ma with the inception of
the Late Cenozoic Northern Hemisphere glaciations. High resolution P:D data
from upper Quaternary sediments show that the peaks in terrigenous influx
correlate with erosional unconformities on the continental margins formed
during or shortly after glacioeustatic sea level lowstands (type 1 sequence
boundaries). Later, during glacial terminations, upper continental margins
become depositional as sea level rises, and terrigenous influx to the deep
sea decreases.
Studies of cores from the Grand Banks (Site MD95- 2031, 1570m) and New Jersey
Slope (DSDP Site 612, 1386m) show that sediments accumulated very rapidly
during Termination I in upper and mid- slope environments of the Northwest
Atlantic. On the Grand Banks, peak P:D values are associated with the cold
Younger Dryas interval, following the meltout of icebergs around 14-12 Ka
(Heinrich event H1) which is marked by high concentrations of Paleozoic
acritarchs. On the New Jersey Slope, thick late Wisconsinan muds, capped
by a veneer of Holocene sediments, unconformably overlies early Pleistocene
or Pliocene sediments. Here, peak P:D values also occurred during the Younger
Dryas cold event but are not found in the meltwater intervals. These P:D
peaks are rich in shrub pollen (birch and alder) not associated with long-distance
wind transport and in neritic (shelf) foraminifera. These microfossil assemblages
appear to indicate resedimentation of glacial marine sediments to the mid
slope during the terminal Pleistocene transgression, in contrast to P:D
peaks in the deep sea that are correlated with more massive mass wasting
or gravity flow events.
___________________________________________
DIATOMS AND SILICOFLAGELLATES AS INDICATORS OF HOLOCENE CLIMATE TRENDS IN
SAANICH INLET, BRITISH COLUMBIA, CANADA
Melissa R. McQuoid1 and Louis A. Hobson2
1Centre for Earth and Ocean Research, University of Victoria, PO Box
3055, Victoria, British Columbia, Canada V8W 3P6
2Department of Biology, University of Victoria, PO Box 1700, Victoria, British
Columbia, Canada V8W 2Y2
Diatom history and climate change in Saanich Inlet can be studied in
great detail over the last 12,000 years because its laminated sediments
are easily sampled at annual and sub-annual levels. Short, frozen sediment
cores provide a record of seasonal diatom changes over the last 100 years,
a record which is similar to species successions observed in the inlet today.
Interannual changes in diatom abundance are observed on a decadal scale,
a trend also found in fish catch records and sea surface properties in other
areas of the northeast Pacific. Longer timescale variations are being examined
from 100 m long cores taken by ODP Leg 169S.
Results suggest that species composition and abundance in the long cores
is similar to the frozen cores as well as recent phytoplankton samples.
The total number of diatoms per gram sediment fluctuates along the length
of the core with years of high concentration (125 million/g) occurring every
600-700 years. Paralia sulcata is very rare in samples below 35 m. Although
the diameter of this species has been associated with changes in temperature
and salinity, there is no obvious difference between valve widths of Paralia
above and below 35 m. This may partly be due to a lack of Paralia cells
deep in the core.
A period of high silicoflagellate abundance occurs early in the Holocene
and may be due in part to an unusual flood event at this time. A database
of phytoplankton and environmental data is being compiled to better understand
the ecology of individual phytoplankton species in Saanich Inlet and surrounding
waters. These data provide the basis for transfer functions which will be
used with fossil records to estimate past changes in climatic parameters
such as salinity and temperature.
___________________________________________
PALYNOLOGICAL CHARACTERIZATION OF A SILURIAN TRANSGRESSIVE EVENT
Merrell A. Miller
Amoco Exploration and Production Technology Group, P.O. Box 3092, Houston, Texas 77253-3092, U.S.A.
A sea level rise following the Late Ordovician glaciation of Gondwana
resulted in several major Early Silurian transgressive events. Global transgressions
became less common in the Late Silurian; however, a Ludlow sea level rise
is widely recognized. The Ludlow flooding event occurred during Polygnathoides
siluricus time and is recognized in paleobathymetric settings that are palynologically
dissimilar. The units were independently dated by either conodont or graptolite
control and their paleobathymetric settings determined by megafossil communities.
The shallowest depositional setting occurs in the Pittsford Shale, Vernon
Formation, Salina Group, New York, which contains a near-shore Lingula benthic
community. The Pittsford Shale is an organically lean black shale, of probable
shallow lagoonal origin. The palynomorph composition of this unit is relatively
diverse but lacks chitinozoans and contains a relatively abundant spore
flora. Also present in this assemblage are eurypterid fragments which indicate
shallow water depositional settings.
An intermediate depositional environment is characterized by the graptolitic
beds in the basal part of the Henryhouse Formation of southern Oklahoma
(northern flank of the Arbuckle Mountains). The transgressive beds are gray
marls with rare graptolites interbedded with fine-grained carbonates. The
Total Organic Carbon (TOC, wt. %) values of these beds are less than 1%.
The palynomorph composition of these marls is dominated by acritarchs. Spores
and eurypterid fragments are absent or rare. An important component in this
transgressive unit is prasinophyte algae (Tasmanites and Pterospermella).
Prasinophytes very often occur in transgressive units and can be used to
recognize episodes of sea level rise and maximum flooding surfaces.
A Ludlow black shale from the subsurface of central Tunisia is the deepest
setting examined. This Ludlow succession is dated by graptolites. The TOC
values can exceed 10%, and the assemblage consists of graptolites and Tasmanites
(or thick- walled Leiosphaeridia). These black shales are considered to
represent a condensed succession characterized by a slow rate of deposition
in an anoxic setting. This depositional setting ensured that a lipid-rich,
nearly monospecific palynomorph assemblage was preserved. The prasinophyte
assemblage differs from the two previous examples that contained diverse
palynomorph assemblages and low TOC values.
In conclusion, depositional facies can be recognized on the basis of their
palynomorph content. Prasinophytes are an important group for identifying
transgressive events in the Silurian, as well as in younger systems, and
are a prominent component of Early Paleozoic source facies.
___________________________________________
EARLY SILURIAN ACRITARCHS AND PRASINOPHYTES FROM THE SUBSURFACE OF SOUTHEASTERN
TURKEY
Merrell A. Miller1, Nihat Bozdogan2, Kaya Ertug2, Gordon D. Wood1, Levent Akça3 and Wally Pierce4
1Amoco Exploration and Production Technology Group, P.O. Box 3092, Houston,
Texas 77253-3092, U.S.A.
2Turkish Petroleum Corporation, Research Center, Mustafa Kemal Mahallesi,
2. Cad. No. 86, 06520 Ankara, Turkey
3Turkish Petroleum Corporation, Exploration Group, Mustafa Kemal Mahallesi,
2. Cad. No. 86, 06520 Ankara, Turkey
4Amoco, Strategic Exploration Organization, P.O. Box 3092, Houston, Texas
77253-3092, U.S.A.
Core samples from the Telahasan 1 well, southeastern Turkey, yielded
a rich assemblage of thermally unaltered acritarchs and prasinophytes. Present
in this assemblage are: Ammonidium microcladum, Baiomeniscus sp., Carminella
maplewoodensis, Dictyotidium sp., Diexallophasis denticulata, Diexallophasis
denticulata medarbaensis, Domasia bispinosa, Elektoriskos spp., Eupoikilofusa
spp., Helios aranaides, Helosphaeridium pseudodictyum, Leiofusa estrecha,
Leiosphaeridia spp., Multiplicisphaeridium spp., Onondagella asymmetrica,
Oppilatala insolita, Pterospermella martinii, Quadraditum fantasticum, Schismatosphaeridium
perforatum, Sol sp., Tunisphaeridium caudatum, Tunisphaeridium tentaculaferum,
Veryhachium spp., and Visbysphaera spp., among others. The presence of Domasia
bispinosa in the core samples suggests a latest Llandovery to earliest Wenlock
age when compared to its distribution in Great Britain, Sweden and North
America.
This subsurface unit is unnamed but is correlative with the late Llandovery/
Wenlock portion of the Mudawwara Formation of Jordan and probably part of
the Qalibah Formation of Saudi Arabia. It also has similarities with the
Tanf Formation of Syria. This unit is palynologically distinct from the
Dadas Formation of southeastern Turkey which contains a Late Silurian to
possibly earliest Devonian assemblage.
Cuttings samples from section stratigraphically below the core also contain
infrequent Early Silurian acritarchs, however, rare specimens of well-known
Ordovician acritarchs such as Villosacapsula setosapellicula, Peteinosphaeridium
and Actinotodissus are present. From the data available, it is not possible
to determine if these fossils are recycled or Ordovician section was penetrated.
___________________________________________
A NEW DESCRIPTIVE TERMINOLOGY FOR DINOFLAGELLATE HORN MORPHOLOGY
Eric Monteil1 and Robert W. Williams2
1IKU Petroleum Research, N-7034 Trondheim, Norway
2Norwegian Petroleum Directorate, Postboks 600, N-4001 Stavanger, Norway
Monteil (1991) proposed a new descriptive horn morphology terminology
for the genus Muderongia Cookson and Eisenack, 1958. Ten types of horn were
recognized: 1 apical, 6 lateral, and 3 antapical in the Ceratioid group.
The aim of this new terminology, applicable also to non-Ceratioid taxa,
is to accommodate a larger range of horn morphologies using a smaller number
of basic criteria. This enables systematic and non-ambiguous diagnoses.
Definitions of different horns types and other morphologic terms are reviewed
and the universality of the concept is demonstrated through different examples
of Cretaceous and Tertiary taxa. This new terminology has important implications
for the conception and development of Dinium-Alpha software.
___________________________________________
AN UNCONVENTIONAL BIOSTRATIGRAPHIC APPROACH: THE CONCEPT OF
MORPHOSTRATIGRAPHY
Eric Monteil1 and Robert W. Williams2
1IKU Petroleum Research, N-7034 Trondheim, Norway
2Norwegian Petroleum Directorate, Postboks 600, N-4001 Stavanger, Norway
The aim of this unconventional approach is to provide an alternative
biostratigraphic method that is independent of the concept of generic and
specific taxonomic units. The alternative method, called morphostratigraphy,
is based on variations of unambiguous morphological features through time.
This new approach offers the generation of multiple events (event-maximization)
that have applications in various fields of geology (biostratigraphy, ecostratigraphy,
and graphic correlation).
Dinium-Alpha's morphostratigraphic logging and plotting functions provide
a tool for recording and processing large amounts of morphostratigraphic
data. This opens a new era in reservoir high resolution biostratigraphy
and modelling, inter-regional and inter-facies correlations, and understanding
of palaeoenvironmental factors controlling dinocyst assemblage composition.
___________________________________________
MID-TERTIARY PALYNOMORPHS FROM DSDP HOLES 94 AND 98 (GULF OF MEXICO AND
BAHAMA PLATFORM)
F. E. Oboh-Ikuenobe1 and A. P. Hoffmeister1
1Department of Geology & Geophysics, University of Missouri-Rolla, Rolla, Missouri 65409, U.S.A.
Well preserved dinocysts, pollen and spores are present in upper Oligocene
and lower Miocene sediments from Deep Sea Drilling Project Hole 94 (Gulf
of Mexico) and Hole 98 (Bahama Platform). Common dinocysts include Tuberculodinium
vancampoae, Dapsilidinium pseudocolligerum, Operculodinium centrocarpum,
Apteodinium australiense, Hystrichokolpoma rigaudiae, Impagidinium sphaericum,
Lingulodinium machaerophorum, and several species of Spiniferites. Bisaccate
pollen and other typical Gulf coastal sporomorphs, such as Carya veripites,
Sequoiapollenites lapillipites, and Quercoidites microhenricii, occur in
the sediments. These palynomorph taxa are long ranging, but the first appearance
datum of T. vancampoae is in the late Oligocene, which suggests that the
sediments are late Oligocene or younger in age. Furthermore, the common
Oligocene pollen Magnopollis micropunctatus is present in some of the samples.
These findings are supported by foraminiferal data, which place the sediments
in the late Oligocene and early Miocene at Hole 94 (P22/N4 and N8), and
at Hole 98 (N3 and N4). Nypa palm pollen is abundant in samples from the
middle part of Hole 94, which is currently located at the shelf break. The
abundance of palm pollen in the sediments was probably related to 1) proximity
of Hole 94 to an ancestral lobe of the Mississippi delta, or 2) offshore
transportation of the pollen by strong paleocurrents.
___________________________________________
HIGH RESOLUTION POTENTIAL OF INTEGRATED BIOSTRATIGRAPHY BASED ON CALCAREOUS
NANNOFOSSILS AND DINOFLAGELLATE CYSTS IN THE LOWER JURASSIC (UPPER PLIENSBACHIAN
- LOWER TOARCIAN) OF CENTRAL ITALY
Raffaella Bucefalo Palliani1 and Emanuela Mattioli1
1Department of Earth Sciences, University of Perugia, 06100 Perugia, Italy
The Umbria-Marche area (central Italy) in an important Mesozoic biostratigraphic
reference area for the Tethyan realm because of the continuity of numerous
successions and the rich micro- and macrofossil content. Because of the
presence of several sections that are well dated by ammonites, this region
is particularly suitable for carrying out integrated biostratigraphy based
on calcareous nannofossils and dinoflagellate cysts. This study is focused
on the late Pliensbachian - early Toarcian, an age interval characterized
by numerous global palaeoecological and palaeogeographical events (i.e.,
speciations, transgressions, and anoxia).
The integration of selected calcareous nannofossil and dinoflagellate cyst
events produced a very detailed biostratigraphical framework. It suggests
that the integration of phytoplanktonic data may represent an important
parachronology to the amonite zonation. The integration of the two phytoplanktonic
groups ensures both a better and more precise biochronological framework
and the possibility to date sediments even when lithologies unfavorable
to the preservation of one fossil group are present. The good resolution
potential of this biostratigraphical approach derives from the different
evolutionary histories of the two phytoplanktonic groups. The light diachroneity
between the Early Jurassic radiation of nannoplankton and dinoflagellate
cysts is linked to the interplay of phytoplanktonic life cycles and global
events. The biostratigraphic framework obtained in the present work yielded
a detail greater than that provided by ammonites and is generally independent
from the sedimentary facies.
___________________________________________
EARLY JURASSIC (PLIENSBACHIAN-TOARCIAN) DINOFLAGELLATE MIGRATIONS AND CYST
PALAEOECOLOGY IN THE BOREAL AND TETHYAN REALMS
Raffaella Bucefalo Palliani1 and James B. Riding2
1Department of Earth Sciences, University of Perugia, 06100 Perugia,
Italy
2British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom
The discrepancies in the stratigraphical ranges of selected dinoflagellate
cysts recorded in the Boreal and Tethyan realms have revealed two migrational
events during the Early Jurassic. The first event occurred at the early-late
Pliensbachian boundary and consists of mutual biotic exchanges between the
two realms. This is linked to a major Early Jurassic transgression which
improved marine communications between the Boreal and Tethyan areas. The
second dinoflagellate migrational event occurred during the mid Toarcian
and was driven by palaeoenvironmental factors. The numerous available Lower
Jurassic dinoflagellate cyst data from the Boreal and Tethyan realms reveals
that phytoplankton distribution was profoundly affected by palaeoecological
factors. Information pertaining to the life strategies and the palaeoecological
requirements of the genera Luehndea, Nannoceratopsis and Valvaeodinium has
also been determined.
___________________________________________
THE LINK BETWEEN THE DINOGFLAGELLATE CYST RECORD AND ORGANIC CARBON CONTENT
IN SEDIMENTARY ROCKS: A PALAEOECOLOGICAL MODEL FOR THE LOWER TOARCIAN OF
CENTRAL ITALY
Raffaella Bucefalo Palliani1, James B. Riding2 and Stefano Torricelli3
1Department of Earth Sciences, University of Perugia, 06100 Perugia,
Italy
2British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom
3AGIP San Donato Milanese, 20120 Milano, Italy
The integration of palynological and geochemical data (Rock-Eval Pyrolysis)
from three Lower Toarcian sections cropping out in central Italy yielded
information on the palaeoecology of selected dinoflagellate cysts, allowing
the indentification of palaeoecological index taxa. The relationships between
the dinoflagellate cyst distribution and the Total Organic Carbon (TOC)
values during the Early Toarcian of central Italy are controlled by palaeoenvironmental
evolution, which produced a variation of the available habitats in the photic
zone and competition processes among specialist and opportunistic taxa.
The life strategies of selected Early Toarcian dinoflagellate cysts have
been deduced by the elaboration of a palaeoecological model based on phytoplanktonic,
geochemical, and sedimentologic data. According to this approach, the composition
of the phytoplanktonic assemblages can give specific information regarding
the stability of the palaeoenvironment and the trophic conditions of the
surface water.
A relationship between life strategies and the evolution of dinoflagellates
may be evidenced. The R-selected dinoflagellate cysts belong to families
and species with wide stratigraphical ranges. Their restricted palaeoecological
tolerances are probably linked to their long evolutionary history. Conversely,
the K-selected dinoflagellate cysts belong to families and species with
restricted stratigraphic ranges. Because of their short evolutionary history,
they probably were very simple organisms, and were able to tolerate various
palaeoecological conditions.
___________________________________________
MEGA-CARBONACEOUS PHYTOPLANKTON REMAINS FROM PROTEROZOIC BASINS OF INDIA:
A STUDY OF THEIR MORPHOTAXONOMY, TAPHONOMY, AND EVOLUTION
Vibhuti Rai
Department of Geology, University of Lucknow, Lucknow, 226007, India
Mega-carbonaceous remains of Proterozoic age have been studied the world
over for their significance in understanding the evolving biosphere during
that time-span. Of late, it is believed that the major biological events
that triggered the Phanerozoic explosion of life have their precursors in
the Proterozoic strata by way of well-developed fossiliferous horizons.
Although rare in occurrence, India is one of the few countries with exceptionally
well developed Proterozoic basins which have yielded definitive evidence
for highly diversified macro-planktic and macro benthic communities. These
basins are located both in the Peninsular India, namely the Vindhyan, Kurnool,
Kaladagi and Bhima basins, as well as in the Himalaya, the Krol and Deoban
basins.
Amongst the mega-planktic community of the Proterozoic, Chuaria circularis
and Tawuia dalensis are the most commonly occurring taxa. These are millimetric
to a centimetre in size, usually preserved as compressed vesicles, and usually
found in the shale/ micritic-limestone intercalations. A detailed analysis
of these fossils indicates that taphonomic factors and morphological features
influence the preservation of the fossils to an extent where a range of
morphologies are generated. A sequential analysis of these forms has been
accomplished by developing a preservational model for these fossil forms.
A host of other associated fossils such as Grypania, Beltina, Lanceoforma,
Longfengshania, and Beltanelliformis have also been recorded from several
horizons of Indian Proterozoic basins. A detailed distribution pattern of
these fossils in lateral and vertical profiles has been drawn. A few newly
discovered fossil forms are described in light of such occurrences from
China and Canada. The exceptionally well-preserved forms from the Deoban
basin in the Himalaya add new information in the establishment of a firm
biostratigraphic scheme for global correlation. Using the distribution pattern,
possible paleogeography and evolutionary scheme for gigantism in the planktic
and benthic communities, these occurrences from India are discussed, synthesized,
and used for generating a biostratigraphic scheme.
___________________________________________
JURASSIC DINOFLAGELLATE CYST BIOZONATION OF THE RUSSIAN PLATFORM AND NORTHERN
SIBERIA
James B. Riding1, Valentina A. Federova2 and Vera I. Ilyina3
1British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom
2VNIGRI, 39 Liteiny Avenue, St-Petersburg, 191104 Russia
3United Institute of Geology, Geophysics and Mineralogy, Universitetsky
Prospect, Novosibirsk 90, 630090 Russia
The palynology of an extensive suite of samples from the Lower and Middle
Jurassic (Pliensbachian to Callovian) of northern Siberia and the Middle
and Upper Jurassic (Bathonian to Volgian) of the Russian Platform has been
studied. The principal emphasis of this study is dinoflagellate cyst biostratigraphy
and numerous key markers have been identified. Furthermore, a biozonation
has been developed.
The Pliensbachian to Toarcian successions of the Anabar Bay area, northern
Siberia are dominated by the genus Nannoceratopsis. The Upper Toarcian,
however, has yielded diverse microplankton assemblages including the Parvocysta
suite and abundant Phallocysta eumekes. Typically Boreal taxa such as Valvaeodinium
aquilonium have also been recorded from the late Toarcian. The Lower Callovian
of Anabar Bay has also produced rich dinoflagellate cyst floras including
prominent species of Chytroeisphaeidia, Crussolia and Paragonyaulacysta.
The Bathonian sediments of the northern and central Russian Platform have
produced relatively low diversity dinoflagellate cyst floras which are significantly
different to those from Europe and surrounding regions. This is consistent
with research suggesting that Bathonian palynofloras exhibit marked endemism.
Protobatioladinium elatmaensis and P.? elongatum are common throughout much
of the Bathonian in this region.
Callovian to Kimmeridgian dinoflagellate cyst associations from throughout
the Russian Platform are similar to coeval floras from northwest Europe
and biozonations developed in northwest Europe can be utilised. The assemblages
are extremely abundant and Upper Callovian to Middle Oxfordian associations
are of particularly high diversity. The ranges of some key species such
as Chytroeisphaeridia hyalina and Lithodinia planoseptata appear to exhibit
heterochroneity between Russia and northwest Europe. These differences in
ranges can indicate miscorrelations of the respective ammonite biozonations
applied to Russia and western Europe. The Volgian of the Russian Platform
has yielded low diversity palynofloras and includes the characteristic 'hot'
shale organic facies.
___________________________________________
MIDDLE EOCENE MANGROVES AND VEGETATION CHANGES IN THE
MARACAIBO BASIN
Valente Rull
MARAVEN.Exploration Dept. Box 829, Caracas 1010-Avenezuela
email: epxg134@bioserv.maraven.pdv.com
As a part of a general project whose aim is to reconstruct the palaeosuccesion
of Paleogene mangroves of the Maracaibo Basin, this work deals with the
quatitative reconstruction of middle Eocene mangrove communities, and their
relation with potential forcing factors. Four pollen assemblages were found
representing respectively, inland forests (A1), back-mangrove herbaceous
swamps (B1), mangroves (B2), and an unknown plant community dominated by
the extinct E. trianguliformis. Mangroves were dominated by Pelliciera and
Nypa, whereas Brevitricolpites variabilis, which has been considered the
dominant taxon of the early and middle Eocene mangroves in nearby areas,
has not been found in this study.
The assemblages found allowed reconstruction of the sequence of coastal
vegetation linked to sea-level changes. The trends obtained constitute a
`palynocycle' which began and ended with a low sea level plant community
dominated by unknown E. trianguliformis and low palaeosalinities, whereas
intermediate high sea level vegetation is represented by mangroves and high
palaeosalinities. This cycle is correlated chronologically with the global
eustatic cycle TEJAS A 3.4, extending from 44 to 42.5 m.y. BP (Lutetian).
The floristic composition of middle Eocene mangroves studied has been very
different from that of the Oligocene to Recent ones. An important evolutionary
change is suggested to have occurred during the late middle Eocene and the
late Eocene in these communities. Pollen taxa botanically related with known
mangrove elements seem scarce for this time span, but studies are yet very
fragmentary. Further research on this respect is strongly encouraged. The
change seems to have been of worldwide significance, as indicated by the
past and present distribution patterns of species like Pelliceria and Nypa.
___________________________________________
THE EVOLUTION OF WILLOUGHBY BOG, ONTARIO, CANADA
Adam P. Sarvis1, James W. Pengelly2, Francine M. McCarthy1, Anne R. Yagi3 and Keith J. Tinkler2
1Department of Earth Sciences, Brock University, St. Catharines, Ontario,
Canada, L2S 3A1
2Department of Geography, Brock University, St. Catharines, Ontario, Canada,
L2S 3A1
3Ontario Ministry of Natural Resources, Fonthill, Ontario, Canada
Sedimentologic data, pollen analysis, loss-on-ignition, diatom analysis,
plant macrofossils and radiocarbon dates were used to reconstruct the paleoenvironment
of Willoughby Bog, Niagara Falls, Ontario, Canada. The paleoecological interpretation
is complicated by catastrophic discharges from Lake Agassiz and Lake Barlow-Ojibway,
changes in outlet routes, isostatic rebound and climatic changes over the
Great Lakes basin. A total of four cores have been obtained in close proximity
to each other at this site. In 1990, Pengelly obtained a core representing
the paleorecord of Willoughby hypothesizing the transition from a fluvial
to a bog environment. The single Pengelly core provided three radiocarbon
dates of 7,670 +/- 240 y B.P. at 290 cm, 7,470 +/- 180 y B.P. at 225 cm
and 6,900 +/- 100 y B.P. at 195 cm.
Sarvis (1997), measured the depth of the organic rich sediments along specific
transects in order to define the cross-section of the hypothesized fluvial
basin. Three cores (WB1, WB2 and WB3) were selectively located and analyzed
along transect B-B' to provide an interpretation of the paleoenvironment.
A radiocarbon date was obtained from core WB1 providing an age of 6,730
+/- 90 y B.P at 210 cm at the beginning of organic sedimentation. The lowermost
sediments in Pengelly"s core and core WB1 records the transition from
a river channel to a bog environment. The transect analyses also revealed
typical channel cross sections.
The results of these analyses support existing models of the evolution of
Willoughby Bog from a fluvial environment approximately 7,000 y B.P. in
response to rising water levels in the Erie basin.
___________________________________________
ACRITARCH EVOLUTIONARY LINEAGES DURING THE ORDOVICIAN
Thomas Servais1 and Stewart G. Molyneux2
1Technische Universitat Berlin, Institut fur Angewandte Geowissenschaften
II, Ernst-Reuter-Platz 1, Sekr. EB 10, D-10587 Berlin, Germany
2British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom
It is very difficult to establish evolutionary lineages for the acritarchs,
as studies on molecular phylogeny are not available and evolutionary models
are essentially based on comparison of morphological characters. Few evolutionary
lineages of acritarch morphotypes have been published. Loeblich & Tappan
(1971) illustrated a perceived phylogenetic trend in the Ordovician genus
Orthosphaeridium. This model has frequently been cited by acritarch workers
as the prime example of phylogenetic relationships in acritarchs, although
it was seriously criticized by Cramer, in Eisenack et al. (1979). Other
examples in the literature are Eiserhardt's (1989) modified model of the
same genus, and the hypothetical phylogenetic relationships of some Ladogella
species proposed by Di Milia, Ribecai & Tongiorgi (1989).
As acritarch taxonomy is essentially phenetic, the first step towards understanding
the evolution of acritarch morphotypes is to select characters which may
be useful for the delimitation of taxa. However, as most parameters appear
to be extremely variable, it is essential to investigate large populations
of well-diversified assemblages to understand the evolution of individual
species. Studies on the variability of several Ordovician taxa reveal that
morphotypes which were originally clearly distinguished by specific characteristics
grade into each other through intermediate forms which combine those characteristics.
The major problems in developing a reliable model of an evolutionary trend
for the acritarchs are the understanding of variability, and the distinction
of palaeoenvironmental and biostratigraphical effects on morphology.
The study of large populations of discrete morphotypes in the messaoudensis-trifidum
acritarch assemblage from the subsurface of Rügen (Germany) may provide
useful information to help understand the evolution of some Early Ordovician
taxa, as this characteristic assemblage can be considered as being transitional
between known Tremadoc and Arenig assemblages. Transients between the genera
Acanthodiacrodium (very abundant and characteristic for many Tremadoc assemblages)
and Coryphidium (a typical Arenig genus) indicate that the coryphid acritarchs
may have originated from the diacrodians.
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"LEIOSPHERES" AND PALEOECOLOGY
Paul K. Strother
Department of Geology & Geophysics, Boston College Weston Observatory, 381 Concord Road, Weston, Massachusetts 02193, U.S.A.
Precambrian and Lower Paleozoic assemblages are plagued by the occurrence
of leiospheres, generally smooth-walled spherical cysts lacking in distinctive
taxonomic characters. These forms are usually considered to be of a marine
origin, following the description of numerous taxa from marine sediments.
The depositional setting of leiosphere-dominated assemblages has been hypothesized
to be both near-shore shelf to basinal, especially following the work of
Dorning in the Silurian Welsh Basin, published during the 1980s.
This class of objects represents a wide range of organisms, but there are
several lines of evidence that may help to establish a non marine source
for a subset of the simple spherical cysts: 1) leiospheres tend to track
with non-marine indicators in the shallow marine Arisaig sequence (Silurian)
of Nova Scotia; 2) a detritivore"s coprolite from Wales is dominated
by spores (indistinguishable from "leiospheres") which gives us
a snapshot of non-marine cysts in the Pridoli; 3) new findings from Middle
Cambrian sediments from the Grand Canyon contain well-preserved "leiospheres"
of probable non-marine provenance, and 4) acritarchous assemblages from
paralic deposits in the Late Cambrian - Early Ordovician of northern Spain
contain a high percentage of leiospheres.
When depositional setting can be determined independantly of palynological
analysis, leiospheres often turn up as a non-marine component. The next
step is to find a consistent set of morphological characters that differentiates
between the marine and non-marine species in this group.
___________________________________________
AFFINITIES OF LOWER CAMBRIAN ACRITARCHS STUDIED BY USING MICROSCOPY AND
BIOMARKERS
Nina Talyzina1, J. Michael Moldowan2, and Gonzalo Vidal1
1Institute of Earth Sciences, Micropaleontology, Uppsala University,
Norbyvägen 22, S-752 36 Uppsala, Sweden
2Department of Geological and Environmental Sciences, Stanford University,
Stanford, California 94305-2115, U.S.A.
The first attempt to characterize acritarchs by application of different
types of microscopy in combination with biomarkers (molecular fossils) and
fluorescence properties of acritarch cell walls is made. Optical techniques
used in the investigation include Laser Confocal Scanning Microscopy, Scanning
Electron Microscopy, Transmission Electron Microscopy, Fluorescence Microscopy
and Transmitted Light Microscopy. Chemical analyses were carried out using
Gas Chromatography-Mass Spectrometry-Mass Spectrometry.
The analyses made it possible to establish links between the studied microfossils
and particular groups of the modern phytoplanktic microbiota. This microscopy-molecular
level combined approach gave new evidence that the group Acritarcha is polyphyletic.
Key biomarkers suggest the presence of Lower Cambrian acritarchs with dinoflagellate
and prasinophycean affinities.
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DINIUM-ALPHA: A CHRONOSTRATIGRAPHIC RANGE, MORPHOLOGY AND PHOTO-MICROGRAPHY
DATABASE BUILDER FOR DINOFLAGELLATE CYST TAXA
Robert W. Williams
Norwegian Petroleum Directorate, Postboks 600, N-4001 Stavanger, Norway
Dinium-Alpha is a database front end application which runs under Microsoft
Windows 95® and NT 4.0®. Dinium-Alpha provides the user with 1)
a palynologically intuitive graphical interface which stores and retrieves
morphological criteria, stratigraphic ranges, and digital images of cyst
taxa; and 2) an identification key which searches for cyst taxa on the basis
of one or more of over 400 user-selectable morphological criteria in combination
with chronostratigraphical range parameters. Morphological and other criteria
are depicted on the graphical interface by self-explanatory icons subdivided
into four main categories: basic morphology, archeopyle type, cyst wall
and chronostratigraphic ranges. Chronostratigraphic ranges are stored and
queried using a scrollable time scale accommodating several search strategies
involving first and last appearances and acme events.
Dinium-Alpha allows the user to search for cyst taxa using any combination
of morphological criteria and chronostratigraphic range parameters. Chronostratigraphic
ranges for individual taxa may also be differentiated according to paleogeographical
or modern geographical realms (i.e., Tethyan, Boreal, North Sea, etc.) and
selectively queried.
Dinium-Alpha is interfaced with portions of DinoSys-Svithjod, a comprehensive
taxonomy and image database application developed by LPP, Laboratory of
Palaeobotany and Palynology, University of Utrecht, enabling the user to
retrieve descriptions and over 8,000 images from the DinoSys database through
morphological queries.
___________________________________________
EVENT MAXIMIZATION THROUGH MORPHO-STRATIGRAPHICAL ANALYSES AND DINIUM-ALPHA
APPLICATIONS: EXAMPLE FROM THE SOUTHERN NORTH SEA
Robert W. Williams1 and Eric Monteil2
1Norwegian Petroleum Directorate, Postboks 600, N-4001 Stavanger, Norway
2IKU Petroleum Research, N-7034 Trondheim, Norway
The concept of morphological character stratigraphy (morphostratigraphy)
was described by Monteil (1990), and defined as "the study of selected
unambiguous morphological features varying in time". Classical biostratigraphy
is based on the distribution of taxa through time, where taxa are defined
by a unique set of morphological characters. Morphostratigraphy, however,
is based simply on the distribution of morphological characters through
time. Morphological characters are treated either as individual units or
as two or more characters in combination, regardless of their taxonomic
affiliation.
It is possible to represent every unique morphological character described
in the literature as an icon on Dinium-Alpha's graphical interface. Such
an encyclopedic interface would enable the user to record an unambiguous
digital description of any dinoflagellate cyst morphotype. Because each
morphological character is represented as a Boolean variable (i.e., present
or absent, or for variable morphology, present and absent), the database
would contain totally quantified descriptions of each taxon. Simple statistical
routines could produce extremely detailed morphological spectra showing
the chronostratigraphic distribution not only of single characters, but
combinations of characters. Other routines could compare the morphological
composition of thousands of taxa, and group each taxon according to overall
morphological similarity.
A demonstration of this method using Dinium-Alpha software is illustrated
in an example from the North Sea. Two 20-meter intervals in two wells from
the Ekofisk Field have been studied morphostratigraphically, with dense
sample coverage (1 sample/meter). Preliminary results show that it is possible
to obtain a detailed and well-correlated subdivision of the studied interval.
Implications and applications of this methodology in reservoir geology are
promising.
___________________________________________
NEW DESCRIPTIVE TERMINOLOGY FOR DINOFLAGELLATE HORN MORPHOLOGY AND ITS IMPLEMENTATION
IN DINIUM-ALPHA
Robert W. Williams1 and Eric Monteil2
1Norwegian Petroleum Directorate, Postboks 600, N-4001 Stavanger, Norway
2IKU Petroleum Research, N-7034 Trondheim, Norway
Monteil (1991) proposed a new approach for describing horn morphology
of the Ceratioid group. The new approach simplified the standard classification
of lateral and postcingular cardinal horn locations and provided a set of
symbols which facilitated an iconographic identification key. The latter
was, in principle, a forerunner to the Dinium-Alpha database builder application.
The Monteil horn classification system has now been implemented in the development
version of Dinium-Alpha. The Monteil terminology has proven more effective
than the standard system in that it unifies a larger range of horn morphologies
using a smaller number of basic criteria.
An important factor in Monteil's horn classification is the concept that
lateral horn morphology results from varying degrees of elongation of the
precingular, cingular and postcingular paraplate series. Therefore, postcingular
horns are classified as lateral horns in which only the postcingular component
is elongated. The forked lateral horns of Nyktericysta spp., the bent lateral
horns of Muderongia crucis, and the right postcingular horn of Pseudoceratium
spp. are simply different manifestations of a single mechanism.
The application of this new terminology is illustrated with examples of
Mesozoic and Cenozoic dinoflagellate cysts.
___________________________________________
THE RISE (AND FALL?) OF A ROCK BUILDER: THE CALCAREOUS NANNOPLANKTON
Sherwood W. Wise, Jr.
Department of Geology, Florida State University, Tallahassee, Florida 32306, U.S.A.
The first calcareous nannofossils appeared in the Upper Triassic (Carnian),
where they are accompanied by the first calcareous dinoflagellates. These,
along with non-calcareous dinoflagelates, filled the microfossil vacuum
left with the demise of the acritarchs and conodonts. Nannofossils increased
in abundance and diversity through the Jurassic, eventually reaching rock-forming
proportions, and helping to change the character of the rocks themselves,
from the "schwartz" to the "braun" to the "weiss"
Jura, in part due to sea level rise and the tectonic opening of restricted
basins. By the Early Cretaceous, calcareous nannofossils were providing
not only the first mechanism for depositing calcium carbonate in the deep
sea, but were doing it so efficiently in the North Atlantic basin that nannofossil
oozes were accumulating at abyssal depths. Micrantholiths and nannoconnids
thrived along the continental margins, but most forms preferred open ocean,
oligotrophic environments. Strong provincialism existed between the Tethyan
and other regions, particularly in the restricted North Sea, where distinct
boreal assemblages developed.
As sea levels and global temperatures rose during the Albian, provincialism
diminished as communication between basins increased and cosmopolitan forms
thrived. Some assemblages reveal Milankovitch cyclicities. Further sea level
rise and the establishment of major epeiric seas caused a shift in the loci
of nannofossil deposition from the deep seas to the continental shelves
and interior seaways, and the great chalk belts (Austin, Selma, English
and French, etc.) that gave the Cretaceous its name were established during
the Late Cretaceous. Nannofossil diversities reached their all-time highs.
The K/T boundary event eliminated about 88% of calcareous nannofossil taxa,
apparently far more than among the less well surveyed dinoflagellates. The
nannofossils extinctions were massive and instantaneous, not step-wise,
and were just as drastic in the high as at low latitudes. Opportunistic
survivors and newly evolved Danian taxa bloomed successively following the
event but at different times at different places, reflecting unstable and
variable conditions around the globe.
The terminal Paleocene thermal maximum is marked by a sudden increase in
the numbers of warm-water loving discoasters, but not by significant extinctions.
Diversities increased as temperatures and sea levels rose during the early-mid
Eocene, but then began a long decline as Earth cooled during the late Eocene.
Discoaster diversities dropped markedly during the cool Oligocene, an epoch
was marked by unusual blooms of Braarudosphaerids in the Atlantic and Indian
Oceans, presumably due to shallow-water upwelling that favored calcareous
nannoplankton rather than siliceous plankton. After a brief climate amelioration
during the early Miocene, global cooling was accompanied by further reductions
in nannoplankton diversity and a constriction of their biogeographic ranges,
particularly in the Southern Ocean. Their decline culminated with the Pliocene
extinctions of warm-water loving sphenoliths and discoasters, but the nannoplankton
have survived as a group; living forms number about 300 species, not all
of which are preserved in sediment. Today their accumulations on the sea
floor are dominated by the multilayered Emiliania huxleyi, which has outstripped
all others in its unique ability to produce and continuously shed coccoliths,
making it the dominant calcium carbonate producing machine of the modern
oceans.
___________________________________________
PALYNOFACIES AND MOLECULAR ORGANIC GEOCHEMISTRY OF THE JATTA GYPSUM FORMATION
(EOCENE), KARAK REGION, PAKISTAN
Gordon D. Wood1, Susan Palmer-Koleman1 and Brenda L. Claxton1
1Amoco Exploration and Production Technology Group, P. O. Box 3092, Houston, Texas 77253, U.S.A.
The Jatta Gypsum Formation consists of buff, dark brown to green and
gray, often gypsiferous, shales. Samples from this stratigraphic unit have
been analyzed for palynomorphs, palynofacies, vitrinite composition and
geochemical fossils (biomarkers) to compare and contrast visual organic
assessments. The Jatta Gypsum Formation yields kerogens composed of 100%
amorphous to mixed (amorphous/terrestrial derived) components and samples
range from organic lean (0.1% TOC) to organic rich (14.0%) indicating different
levels of organic matter preservation.
Stable carbon isotopes of organic extracts and palynological analysis exhibit
a strong correlation and suggest three facies are present. The uppermost
sample in the section contained a monospecific assemblage of an undescribed
dinoflagellate, suggesting a stressed depositional environment. Biomarkers
show abundant dinosteroids and bacterially- derived hopanes. Intriguing
organic remains resembling "diatoms" and "granular"
amorphous debris were isolated from the middle part of the section. This
interval contains abundant algally- derived steranes, phytane and a C25
isoprenoid attributed to diatoms. Abundant reworked Jurassic dinoflagellates
and spores (e.g., Gonyaulacysta jurassica, Nannoceratopsis pellucida, Omatia
montgomeryi, Scrinodinium crystallinium, Callialasporties dampieri) and
in situ palynomorphs (e.g., Homotryblium tenuispinosum, Muratodinium fimbriatum,
Polysphaeridium zoharyi, Tiliaepollenites sp., and Retitricolpites sp.)
were recovered in the organically lean lower part of the exposure. This
interval contains oleanane, a higher plant indicator, and a distribution
of dinosteroids distinct from that exhibited in the uppermost monospecific
dinoflagellate assemblage. Vitrinite composition in this part of the section
is bimodal indicating the reworking of land-derived organic matter.
___________________________________________
PALYNOLOGY, PALYNOFACIES AND PALEONTOLOGY OF THE PENNSYLVANIAN PERMIAN COPACABANA
FORMATION, PERU
Gordon D. Wood1, Greg P. Wahlman1, John R. Groves1 and Paul L. Brnekle2
1Amoco Exploration and Production Technology Group, P.O. Box 3092, Houston,
Texas 75253-3092 U.S.A.
21 Whistler Point Road, Westport, Massachusetts 02790 U.S.A.
Analyses of palynomorphs and calcareous microfossils from sections of
the Copacabana Formation, exposed along the Rio Camisea and Rio Urubamba
(Pongo de Mainique) indicate that both Pennsylvanian and Lower Permian rocks
are present. The Pennsylvanian (Morrowan/Atokan) Foraminifera and associated
calcareous microfossils include Eoschubertella mosquensis, Millerella extensa,
M. marblensis, Biseriella parva group, Calcitornella sp., Consobrinella
sp., Diplosphaerina inaequalis, Earlandia elegans, E. minima group, Endotaxis
brazhnikovae, Endothyra sp., Endotyranella sp., Globivalvulina bulloides
group, Monotaxinoides transitorius, Palaeonubecularia sp., Planenodothyra
aljutovica, P. sp. and Tubisalebra sp. This foraminiferal assemblage displays
strong affinities to the United States midcontinent, Solimõmes and
Amazon basins of Brazil, and the Madre de Dios Basin of Bolivia. The palynomorph
assemblage includes Potonieisporites sp., Protohaploxypinus sp., Spelaeotriletes
sp., ?Striatoabietites sp., undescribed taeniate bisaccates/striate monosaccates
and the fungus Reduviasporonites stochiana. Kerogen preparations are dominated
by terrestrially derived plant debris.
The Lower Permian (Wolfcampian) calcareous microfauna includes the fusulinaceans
Pseudschwagerina ayacuchensis, P. broggi, P. díorbingnyi, P. vilcanotensis,
P. uddeni, P. kozlowkii, Schwaterina munaniensis, S. aff. S. bowmani, S.
spp. indeterminate, Schubertella cf. S. kingi, Triticites peruensis and
T. titicacaensis; the smaller foraminifera Nodosinelloides aequiampla, N.
sp., Syzrana bella and S. confusa; and calcareous alga Fourtonella johnsoni.
The fusulinacean taxa exhibit clear affinities to Late Wolfcampian faunas
of the midcontinent and southwest United States, but relative ranges of
fusulinacean taxa and faunal associations in Peru appear to differ somewhat.
For example, medium-sized Triticites spp. in Peru that resemble typical
Late Pennsylvanian species in the United States are commonly associated
with Pseudoschwaterina spp. and Schwaterina spp. of Wolfcampain age. Also,
according to earlier publications, the uppermost Copacabana Formation displays
a mixing of fusulinacean types that characterize the Late Wolfcampain species
in the southwestern United States, but also contains associated taxa more
typical of the Late Pennsylvanian and Early Leonardian faunas of the United
States. Palynomorph recovery from the Lower Permian was not very good or
yielded non-diagnostic forms, and is believed related to the absence of
suitable lithologies.
___________________________________________
DATING THE RADIOMETRIC DEAD-ZONE: AGE CONTROL IN MODERN MARSHES FOR THE
MISSISSIPPI BASIN CARBON PROJECT
J. H. Wrenn1, J. B. Pracht2, C. M. Fraticelli1 and B. M. Samuel1
1Department of Geology and Geophysics, Louisiana State University, Baton
Rouge, Louisiana 70803, U.S.A.
2Department of Geography and Anthropology, Louisiana State University, Baton
Rouge, Louisiana 70803, U.S.A.
The goal of the Mississippi Basin Carbon Project (MBCP), part of the
U. S. Geological Survey Global Change Research Project, is to understand
the role in the global carbon cycle of terrestrial carbon sequestered in
the Mississippi Basin. The project seeks to quantify the interactive effects
of land use, erosion, sedimentation, and soil development on carbon storage
and nutrient cycles within the basin.
Age control is required to establish sedimentation rates for marsh sediments
deposited between AD 1750 to AD 1900 in a core taken from the Conseil Plantation
(St. Bernard Parish, Louisiana). This "radiometric dead zone"
could not be dated reliably with standard radiometric techniques. The integrated
use of microscopic remains (i.e., pollen, spores, phytoliths, diatoms, carbon
spherules{CS}, and charcoal), and historic records provided the required
age control and potential correlation points.
Three intervals were differentiated:
ca. 1830: based on the first appearance of coal- or wood(?)- generated CS (coal was first shipped to New Orleans in 1829); an increase in Compositae pollen, and the presence of Vigna luteola (Cow pea) pollen. This legume adds nitrogen to tired soils and was grown alternately with sugar cane on the Conseil Plantation as early as 1828. Sugar cane rarely flowers in south Louisiana and its pollen is easily confused with that of other members of the Poaceae family. V. luteola is used here as a proxy for sugar cane production.
1860-1880: maximum abundance of coal/wood CS and a drop in TCT (mostly Taxodium) due to clear cutting of the local Cypress swamps.
1900-1910: advent of oil-generated CS, probably from ships.
___________________________________________
MESO- AND NEOPROTEROZOIC ACRITARCHS IN CHINA
Yin Leiming
Institute of Geology and Palaeontology, Academia Sinica, Nanjing 210008, People's Republic of China
In the Early Mesoproterozoic Changcheng series of North China, acritarchs
are dominated by simple sphaeromorphic forms, and specimens with membranous
envelopes which, in comparison with prasinophites, appear firstly. Up to
Late Mesoproterozoic strata, spheromorphic acritarchs are still common but
edromorphic taxa also occur. Exceptionally, some acanthomorphic acritarchs
such as Shuiyousphaeridium, Tappania, and others, have been found from the
Late Mesoproterozoic Ruyang Group on the northern slope of the Qinling ranges.
In the Early Neoproterozoic, acritarch assemblages from the North China
are characterized by sphaeromorphic and polysphaeromorphic forms, and similar
specimens of Asterocapsoides, Trachyhystrichosphaera, and others also appear
in the assemblage near the Late Neoproterozoic glaciation. Large acanthomorphic
acritarchs have been obtained from cherts and phosphorites of the Doushantuo
Formation in South China at the stratigraphic interval after the Late Neoproterozoic
Nantuo glaciation and just before the radiation of the Ediacaran fauna.
During the duration of the
Ediacaran radiation, acritarchs were distinctly reduced in their abundance
and diversity. Small acanthomorphic taxa such as Micrhystridium, Filisphaeridium,
and others occur in the strata near the boundary between Neoproterozoic
and the Early Cambrian in South China.
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